Funny anecdote (though I've never been to burning man): There is a very common practice of shirt-cocking, where men only where shirts and nothing on the bottom. A brigade of annoyed burners decided to solve this with a pants cannon. The range was good and the platform was mobile, and shirt-cockers would get bombed with pants and everyone would laugh at them.
That mass of laughing people pointing at the shirtcockers also helped. Community policing with editors that have big guns is already pretty common on the internet. Here we have flag options for the community, and a set of editors. To shoot pants at shirtcocking trolls.
So, yeah, there is _some_ policing.