but it does get policed. I've reported chat spammers and users making threats. both resulted in bans.
so i'd say it is best described as egalitarian chaos.
think of it as a chessboard at a sidewalk cafe. not every conversation around the board is about chess, right? do we kick people out for chatting about politics or picking each other up? of course not. it's a busy sidewalk. don't like it? leave.
Just look at a top game and open chat, and it's crazy. They are swearing, spamming, etc. It cannot be controlled.