User blog comment:Link is a Master/Disabling Anon edits/@comment-17737991-20141103032847

The only major vandalism attacks I've seen have been from account users. Sure some petty anon replaces a pasta with "penis" every now and then, but it's not anywhere near frequent or bad enough to justify closing off a huge number of users by requiring an account. And like Flaky mentioned, they'll be banned regardless of having an account or not. If a spammer's going to be a chronic problem, it won't matter if we disable anons due to IP changing. If most anons aren't going to be a chronic problem, and most aren't, there's no point to blocking /all/ of them.

Either way, we acheive nothing but blocking site users who don't have an account.