It's also disconnected incentives. SO users get numbers to go up by taking moderation actions so of course they do that. Also you literally get banned from reviewing questions if you don't flag enough of them to be closed. These are incentives put in place by the SO company intentionally.

It's not like only slimy people get to use moderator tools like on Reddit, since you need a lot of reputation points you get by having questions and answers voted up. It's more like (1) you select people who write surface-level-good answers since that's what's upvoted, and they moderate with a similar attitude and (2) once you have access to moderator tools you're forced to conform with (1) or your access is revoked, and (3) the company is completely incompetent and doesn't give a shit about any of this.