IP bans are usually a bad idea as well for several reasons.
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Regardless, IP bans get served. It's pretty rare that someone gets damaged because of this.
Wasn't there some other spammer that kept naming his accounts "IWillNeverLeave" or a variation of it in the past? He promised that he wouldn't ever go away but I haven't heard much of him recently.
I'm not sure about the past, however there are a recent one who created over 10 000 accounts and has yet failed with his attempt.