Maybe I'm seeing things through rose-tinted glasses, but I've been in the hobby for a pretty long time and ran many open tables and convention games with people I've never met before and I've never seen somebody who isn't reasonable enough to reach an agreement on pretty basic things.
I think if there's a case where a player and the GM just can't agree on something, then there's some deeper problem
a) The player doesn't feel like they are in the same boat as the GM and aren't enemies
b) There's something unclear about what kind of game the group is playing, what the genre, the tone, the theme and the focus are
c) They fundamentally want some different things, but for some reason are still playing together
d) Someone is a complete idiot, but I seriously doubt that complete idiots engage in a such niche hobby in the first place
None of these problems is gonna be solved by expression of authority. The first one is probably gonna just get worse.