It isn't new users who are making most low-quality comments. It's mostly people who've been here for years and should know better.

Sometimes they make new accounts, of course, especially if we've banned them many times - but even those (what you could call) bad actors are not the bulk of the problem. The bulk of the problem is (what you could call) normal users, who would probably be surprised to find this out, since it's human nature to see such problems as caused by others, not self.