Do I really have to point out that this is a lot of "probably"s that need more checking? Last time you used a mob you did nearly kill everyone except the mathematical abomination Anomander's playing in a single round.
Well, that was more fault of too much pimping of the gestalt enemy on my part than the mob rules. It is not easy to properly calibrate encounters when indeed attacks that nearly kill some party members only deal moderate damage to other party members.
Yeah, the Trojan War where Achilles was unstoppable until a god specifically took action to take him out.
Paris was the one sniping Acquilles. Some versions of the story have Apollo Aid Anothering him, but then Acquilles also had gods cheering him on too.
The same Greek Myths where half of Herc's labours were killing things that couldn't be swarmed by sheer numbers. At which point they go spend the next ten years holing up inside of their walls rather than coming out to fight--that's a siege, not a battle.
Nemean Lion-original legend is that he would kidnap damsels to use as bait and then disguise as them to get a surprise round in the warriors coming to save them. Why go through all that trouble if he could just slay any amount of puny humies? Also one of the story's versions had his mouth being as soft as normal lion so Hercules just kites him until he hits the weak point for massive damage. Even if you assume his mouth was also invulnerable normal humies could've defeated it by strangling with ropes or something, but it's a bitch to get armies to go into caves, in particular when there's more pressing matters than a missing person or two.
Lernaean Hydra-Raised by Hera specifically to kill Hercules. No mention of any particular anti-mob ability. In particular when you can just kill it with fire.
CRAB BATTLE!-Completely normal crab that happened to be around and Hera just threw it at Hercules to see if the Hydra could get a flanking bonus or something. Defeated by being stepped on. Not very clear if Hercules ever noticed it besides the crunching sound beneath him.
Ceryneian Hind-By now Hera has run out of dangerous monsters and just tries to screw Hercules over with a non-combat challenge. Really fast, but otherwise not dangerous at all.
Erymanthian Boar-More of a hit and run monster. Hadn't been killed yet because it only bothered farmers, and the greek weren't in the 7 samurais spirit of helping filthy peasants.
Stymphalian Birds-Again, another hit and run enemy. But just as many modern people, Hera kept forgetting that Hercules is a pretty good archer. Filthy peasants that were being eaten before can't afford proper bow however and again the local authorities didn't care to send any proper defense.
Cretan Bull-Hadn't been killed yet because it had been a gift from Poseidon and you really don't want to piss of the god of the seas when you live on an island. Also the local king's wife was made to fall in love with it so she probably had a say to keep him alive. Was tame enough to be shipped off by normal humies and sacrificed by normal means later on.
Mares of Diomedes-Actually raised to be bloodthirsty monsters by a humie, Diomedes himself. Yet Hercules gets to calm them just by bringing some random humies to make some Handle Animal checks. Also feeding them fresh meat. Either way strength in numbers!
Belt of Hippolyta-Not a monster, but again Hercules bets in strength in numbers.
Cattle of Geryon-Hercules kills some two-headed dog and three-headed giant nobody had heard off before. Then almost gets beaten by a river. Didn't get to bring hired help to build a bridge/boat because he had to cross a desert.
Apples of the Hesperides-Main problem was getting there in the first place. Antaeus could be beaten by a simple lever, Ladon may or may've not been there but again, carrying an army there would've been pretty hard work.
Cerberus-The guard dog of the Netherworld. His owner Hades says that using metal tools wouldn't been cheating so most certainly a bunch of soldiers with lots of pointy metal would've done the poor puppy in. But good luck marching an army to the gates of the underworld.
What about Beowulf, with the minor issue of "well, our soldiers can't do this, but this one guy can".
Ok, one story.
And LotR? Bad example. Yeah, the named human characters can be overwhelmed. Gandalf and Sauron? Nope. Gandalf survived every mortal battle he was ever in without issue, and Sauron's being defeated by the Last Alliance? It wasn't the numbers; he was single-handedly stopping an entire army by smashing it to pieces. It was one of the four named characters in the battle (two of whom were dead) who basically scored a crit. That isn't a mob of low level characters, that's an out-of-CR boss fight with NPC's to soak up damage for a bit. The rest of the setting is even worse. Nazgul? Named characters and they were generally operating as generals in the past. But go back to the Silmarillion and it's even more skewed: the earlier parts of the war include an entire army refusing to engage with a single elf who went to take on Morgoth. Or single entities radically changing the tide of battle--Ancalagon is a great example of "and no amount of numbers is going to help against a max-size dragon".
Remind me, what happened after the big battle against Sauron?
HumiewhokilledSauron: Woot, let's return home to celebrate!
DM: Let me roll random encounters. Ok, a bunch of orc remants show up. Roll initiative!
HumiewhokilledSauron: Please, I just killed Sauron, what can some basic orcs do against mMY SPLEEN! GGAAAAAHHHH!!!!(dies to disorganized mob of orcs)
Also as a reminder, the only reason Sauron was fighting in the frontline on the first place was because his army was crumbling (since the humie/elf heroes were fighting on the frontline along the elf/humie mooks) and Sauron had nowhere to run.
And even in the Silmarrion armies were relevant and got shit done. The only reason orcs exist was because somebody decided they needed faster breeding mooks.
TTGL ultimately resolves to "what can a single party do against a single enemy" and any groups are totally sidelined. There's certainly no army in Getter Robo Armageddon or New Getter Robo. Gunbuster and Diebuster's biggest fights are sans army. Code Geass pretty much operates in a space of "the newest mecha eclipse the common stuff by such a margin they aren't worth considering". NGE doesn't have much of a role for armies or numbers.
Eeerrr, Gunbuster's grand finale is they gathering a massive army to zerg rush the enemy spawn camp. Diebuster's robot girl's main ability is having a zillion mecha mooks at her command. Lelouch's main trait is that he can rally a bunch of random peasants armed with smuggled/stolen weapons into an effective fighting force and Code Geas's grand finale has Lulu blocking the super flying fortress's nukes by literally throwing nameless mooks at them. NERV's base is completely crushed by a regular army despite having tanked multiple angels and EVA-2 gets beaten by mass produced models.
But more in particular, shame on you for forgetting Armageddon's
Jin's Tower.
And then there's the full getter mob attack in SRW Z3. Never enuff Getter.
New Getter Robo does cut down on the army bits, but then it also cuts down in a lot of classic Getter stuff. Can only put so much in so few episodes.
There's pretty much a lot of examples either way. There's no universal rule that a large group of weaker enemies must be threatening and at a certain point it stretches much credibility: how the hell are these weak groups acquiring all the items they need to do any damage?
Well the basic idea is that pointy sticks never become fully obsolete.
I thought it was availability. The XP required for levelling rapidly increases as you go up in level, yet the valid sources of experience diminish--essentially, you end up in a world where most enemies aren't challenging enough to learn anything. So you maintain an army of mostly level 1 warriors because they're capable of dealing with most low-level threats, and a large polity will have some medium and maybe high level characters around to deal with monster incursions etc. that are otherwise impossible to handle. It's pretty much how adventurers are justified: there aren't enough high level people available to DEAL with these and only relying on the few high levels leaves you with a defence full of holes that a low level army can actually rush through because the higher levels can't be everywhere at once.
XP to level goes up, XP available goes down, and higher levels are exponentially rarer. Having a high levelled wizard basically makes you a nuclear power, but that means you can afford bigger armies in the first place. One's more economical than the other.
You're assuming that everybody has to grow with exp.
But on their natural state, most monsters simply grow stronger (dragons) or just spawn strong. And sometimes they can multiply by themselves (slaad, wights). Wizards can create minions by a variety of ways. Any civilization will lose by simple attrition if they must wait until heroes level up by exp to be able to defend themselves from D&D's ecoloy.
Heroes are still quite important as high mobility strike forces, since it's a lot easier to transport a few high-level dudes around than hundreds/thousands of mooks. In particular when the mooks need to eat and breathe and stuff.
And "keeps them from being swarmed" is the point. You don't have highly powered characters utilising large amounts of weaker allies for the damage potential, it's so that they don't get bogged down and left vulnerable to other high powered characters or kept from reaching some objective in time. "Uncoordinated but large mobs being as inherently lethal as boss enemies" is a little strange at higher levels.
Again, just ask the guy who took out Sauron with nothing besides a broken piece of metal.
Or the last lotr dragon. Ever wondered how his kin was driven to extinction? Well, as soon as he poked his head out, got critted by a peasant's lucky arrow. The only reason he ever conquered the mountain is because lotr dwarves have neither guns or crossbows and seem to hate bows, so fly-by attack+breath weapon wins the day.
So you're fine with rolling dozens/hundreds of rolls for all the mooks?
It's called Aid Another.
They attack in sets of 10 to 30 or so with reach weapons, everyone else in the group aids the single attacker - reduce size of attackers and/or make them flying creatures if you really need to pile the numbers on a tank or brick. They will hit the PCs, even with 30-50 ACs, or more. This method reduces the dice rolling to one roll per set of 'x' mooks. doable even by physical dice. For the Aid Another check, I can either fiat/assume a success or a certain percentage of success every time, roll one more die to determine how many succeed (yes, I have a 30 sided die), or I can roll them all using my next comment.
Besides, I have the best dice roller on the planet. It can handle up to 1000 rolls in a few seconds. Write the dice script ahead of time, push the button, and it sorts the results however I want. So if I wanted to, yes, yes I could roll for dozens or even hundreds of mooks in just a few seconds.
I don't suppose you could share your super script with us?