My games these days are pretty permissive. Not quite the yes-first utopia described in the opening, but what I've found through the years is that trying to list a billion rules to govern behavior just doesn't work. The good players feel constricted, and the bad players ignore and/or don't read the rules and have to be dealt with anyway.
That said, I think it's important to set limits on several key points. Others have outlined several already in terms of consent / FTB. Alts is another good example. The utopian view is "let people play what they want and it'll sort itself out". I thought that way myself until I saw how the departure of a once-active player with 4+ alts gutted my small game because so many characters had key relationships with theirs.
Chargen apps is another. I played on / ran a couple games where chars were allowed to hit the grid provisionally and were audited after the fact. Man what a disaster that was. Never again. I keep my chargen/app process VERY lightweight and ultra fast, but I've found that it's an essential gate for filtering out people who can't even clear the smallest thematic bar.