This happens when people get too attached to a forum and forget that it isn't their very own playground.
I wouldn't even bother to ban such people because then they just change their identity and it makes it more difficult to ignore them. Yes, ignore them, that's all we can do with stupid people because they are everywhere anyway.
If we all ignore them, they will soon get bored by creating new threads only for themselves to read.
Or let them play only with each other, lets see how long their friendship will last.