This thread comes up on every RPG forum about twice a year. And every time I'm struck by the differences in my 40 years of experience playing RPGs, and the theorycraft and prescriptions bandied around online. Anyway, in my experience:
* Most players don't want to collaborate on building a world, deliberately crafting a story, or developing sub-systems and houserules. They just want to play their PCs. This narrow focus is one of the main draws of being a player, and why most players don't want to ever GM.
* Given the narrower focus that players have, they often don't consider how their wants might negatively affect the rest of the players, the game system, or the DM's campaign. Which doesn't mean they're obnoxious or selfish - they just aren't in a mindspace where they're concerned about whether their stack of ranged attack abilities overshadows other PCs or makes the GM's campaigns less challenging or satisfying.
* This makes the GM the obvious choice for making the final call when a) something comes up that isn't covered in the rules, b) the game or campaign is getting unbalanced, and c) the group doesn't quickly agree on a solution to a or b. The GM, by the nature of their role, handles big-picture matters in the game. Just as a coach on a sports team is concerned about more than the play of an individual, and the director of a play is concerned about more than just the performance of one actor. And yes, there are sports teams that manage without coaches, and plays that are wholly collaborative and have no director. But both are rare, and with good reason.
In tabletop RPGs, GM authority is a practical consideration more than anything. Few people enjoy a session getting bogged down in debates or looking up and interpreting rules. One of the core jobs of a GM is to keep the game moving. I suspect this is why my experiences at the table are so different from the opinions bandied about on forums. At the table, a decision needs to be right away, in real time; whether that ruling is perfectly balanced mechanically, or respects egalitarian ideals and the right to self-actualization of everyone at the table are only considerations when sitting back in our chairs, puffing metaphorical pipes, and tapping away on our keyboards for hours and days on end.