Steve Summit wrote:
When you see someone with a big, fancy, "cutesie" signature, it is obvious that (a) they spent a lot of time on it, and (b) it is very personal to them, it is part of their identity. Yes, you and I think it's silly and inconsequential, but to them it's very important. So when you delete or alter it, it's a direct personal affront, a slap in the face, the equivalent of an ad hominem argument. They react angrily, and this should come as no surprise.
So send them off to read WP:OWN and WP:NOT, and in the meantime check out the bit on every edit page about "merciless editing".
Anybody who complains about anything they add to Wikipedia just about anywhere other than their own user-page being edited mercilessly needs to be handed a bunch of clues.
If that does not work, a few sharp taps with a cluebat should help, and if they still insist on their "right" to scrawl graffiti across the encyclopedia, then maybe they should take time out to sit on the naughty chair and think about their activities. If it works for naughty children, it should work for them.
Obviously some people are simply not educable in this fashion and will just have to be shown the door.
HTH HAND