Ah i see.
All those points are fair examples though I will say I think the reason GM abducation has become relegated to always become a lengthy discussion / debate is directly related to the fact that earlier editions of dnd were so rules heavy and content wide that a player who's always read up, could usually find some rule in book to deny what the DM wanted to do. Or simply because the DM doesn't know every class, prestige, feat and item by heart, it created this cenario where the player's knowledge base could be so outside the DM's because of all the extra content the DM would end up discussing it anyway.
This always makes people forget the rule stated near the beginning in most of the PHBs i've read that says the DM is god, if you don't like the game, leave.
I admit that this, especially the bolded portion, baffles me. It makes it sound like it's the DM's game, and we're just inhabiting it. If that's the case, then the space between D&D and fanfic is extremely small. Further, it's inimical to how I think the game should run. The gameworld consists of an environment that hopefully makes a bit of sense: big dragons have armor like tenfold shields, it's hard to kill ghosts with the average stick, etc. And, then everything comes together to create scenarios and interesting challenges and unanticipated responses, and so on. If the DM's hand is on the wheel the entire time, then there's not much game there anymore.
Now, while a player should always know their shit, I feel like 5es vagueness give me the right as the DM to really be god.
...
So... yeah, I'm just a fan of the system that goes, player ask for something, DM decides. end of story even if DM takes 10 minutes to think about it out of session.
If that's the case, why are rulebooks that are several hundreds of pages long even needed? It seems that a system at this level of adjudication could fit within something in the neighborhood of 40 pages, if that. I'm not morally opposed to such a system -- I probably wouldn't be that interested in playing or even running it, but that's a taste of mine. But, it seems odd and counterproductive to hold that up as an ideal and at the same time produce books chock full of rules that, I'm gathering, end up being vague or misleading.* Either make it rules-lite and lean heavily on DM adjudication, or make whatever rules that you are going to write clear and to the point. It seems like the game wants to have it both ways, but this tension can only lead to problems.
I also happen to think that putting cool ideas behind a "DM May I?" paywall stifles creativity. Every cool combo or what have you that I'd come up with has to seek permission, which means I'm stuck building Amon the Swashbuckler the way the DM thinks I should buckle swashes. Seeing as the main appeal, I think, from a system as fiddly and D&D has traditionally been** is coming up with new, interesting, and often unanticipated combinations of abilities, this seems like a problem.
*Caveat: I have only skimmed the 5E rules and played a playtest of it (which, to be fair, did not impress me with the system at all ...). So, my judgments on these things are based on what people have been saying in threads like this.
**Just to head off any arguments, D&D has been a fiddly combos-oriented system for a
long time. I'd go so far as to say it's part of it's brand identity. Meaning this kind of thing isn't an advent of 3E, it just changed some of the bits that you could use.