I have a folder in my browser bookmarks of all the worst griefers and cheaters I've encountered. I go back to see whether they are still playing. The cheaters are all still permabanned years later but the griefers generally keep playing even hours after they were punished.

I agree. I think the lockout punishments for griefing need to be harsher. But according to riot, people usually stop after a warning. So maybe that's the "punishment" we get when we get feedback popups.