I don't think players having authority over something more than their players automatically leads to the sort of thing you're describing, or the world not making sense--and I say that as someone who prefers to lay the game world's foundations and large-scale things solo, as GM, because I have things I want the game world to be and not to be.
I have had a player go a little overboard in writing his character's backstory, but A) it was a tragedy, B) it didn't make the world not make sense, C) the player now realizes (without my explicit prompting, I think) he went well over the top and D) I have learned to ask players to keep backstories kinda short and to remind them their characters are closer to the beginning of their story than the middle, let alone the end. (And I think that last works, even if you expect the story to be understood mostly looking backward.
I am familiar with the stammering and muttering, but I think some of that is about knowing your players. I have never seen a player who understood what they were being asked exceed the ambit of their authority, or try to.