^ sort of. I say "sort of" b/c I've played with the same 3 or so gaming groups for the past few years, and we pretty much never categorically ban things. But, I can readily see how someone would have a rougher time playing a Paladin (holy warrior not entirely dependent on spells) or an Unarmed Fighter archetype without ToB, for instance. You'd just be encouraging them to pick something else. Sure, there are other concepts out there, but it's a cost to the game and the campaign when someone doesn't get to play the (reasonable and genre-appropriate) thing they want to play.
I will freely admit that one of my chief values in a rules system -- and source banning or not is part of a rules system -- is that it supports the widest array of character concepts (conditional on the setting, etc.) in interesting ways.
With regards to these comments:
Is that really your experience? In the campaigns I have been DMing or playing in, optimization was never the condition sine qua non. Sure, sometimes players would grumble a little that they can't play a Warblade because ToB is unavailable for some reason (not necessarily outright banning), but a likable alternative is usually found. Most RPGers I know like to play to a concept regardless of whether it will be as effective as the Wizard, Cleric or Druid.
Put another way, no game I've ever witnessed had NO tier three, four or five characters in it. It's the DM's job to make it work, and the whole group's job to make sure everybody's having fun. If that requires the casters to tone it down at high levels, so be it. And if it requires you don't even go to the highest levels, so be it, as well.
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Yes it makes less character options viable. Doesn't really matter, there are plenty of options left in the pool, and as experience so far demonstrates, what we in CO consider basic performance will cream anything of regular difficulties to begin with.
2 thoughts. First, I don't love the tiers system, as I think optimization corrects a lot of the disparity between the "raw" classes (I know the tiers are controlling for optimization, which is part of why I don't like them). So, yeah, a group with a Ranger and a Conjurer in the party can be totally balanced. I've played that Ranger and had a blast. It just took a little bit of work on my part, but that's actually a part of the game I enjoy. My gf is playing a Soulknife who is pretty awesome. And, I agree with Veekie, the goal is not the most powerful build possible or anything, it's just that it be viable and fun and do what it sets out to do. You just want to avoid warriors that can't fight and stuff like that, they don't have to be zomg! awesome.
Second, it seems that these are more shifting the DM's burden around than eliminating it. It's her job to "make the power disparities work." It's unclear to me whether that's really any more work than reading an executive summary (or even the entire ruleset) for something like ToB. This is especially the case in running modules and adventure paths.
This may come down to a difference in DM style. I sort of prefer to rely on my players knowing the benchmarks, or communicating them explicitly to them, and then running challenging encounters and seeing what they do about it. There's not a lot of tailoring in that style. Others, including some of my best friends and some of the best DMs I know, prefer to tailor the encounters more to the PCs.
Just to circle back a bit, I do think if someone has to scratch a particular concept they had in mind for rules reasons, that's bad, and significantly so. And, I'm not sure digesting a bunch of ACFs, obscure feats, and synergies that it would take to make a Paladin perform the way you'd expect it to is any easier than just letting someone play a Crusader.
P.S.: I think this is a really interesting discussion, and appreciate everyone's thoughts and, to be blunt, the tone of it. Things can get kind of ... acrimonious online, especially on these things, and I don't think this thread has.