actually, some people should see a warning, if one person did it once cause someone really annoyed them and got banned already and others come and flame in every thread and both get banned, then it's unfair for the first person.
Back to the topic:
Some threads are being shut down as Storm said just to do the clean up before more posts appear that will need deleting. I ahve seen that happen several times and it's a good way for mods to deal with it. After cleaning up they reopen the thread unless they see that the thread maker can't take controll over their thread or he/she created it to actually start a flaming like this
