Complete lawlessness and anarchy, I can see how that could turn bad. Even in the absence of physical violence, if people decide that someone should suffer to the mob, having an authority of some sort is kinder. Wild West jails were more about protecting the criminal from the town.
We don't have lawlessness and anarchy. I mean, we sort of do, but. There are controls other than "ban". We have a lot of people whose posts have to be vetted by moderators before they appear, including me. Most of them have requested this and/or explicitly prefer it to not-being-moderated, because it reduces the risk that they'll screw up and have problems they can't deal with.
Yeah, @Greallan, the lack of bans is sort of a core feature - the stickied threads in this subforum, specifically the Read This First and the FAQ can explain more, and some of the other options available.
I still owe y'all an actual writeup of the underlying mod philosophy and some of the decisions around here, which are decidedly non-typical.