It really doesn't matter. Mods should focus on fixing problems, not problem posters. Sure the problems we are talking about may be because of a few posters, but any rules should apply equally to everyone and all should have chances to change their behavior. Of course, some posters have never changed their behavior in response to any corrective or disciplinary action and that's really how they got to be a problem. But that's their problem.
How do you fix problems when the problems are the behavior of people, and you can't fix the people?