Hello Figge!
If it were any formal text I'd agree with you. But that's a typical message from a chat and Tiago would never understand why only he writes 'want to' to say the same thing.
Thus I wrote a note commenting that.
PS: usually when people are chating they try to find a way to type as fast as they can, and sometimes they even have to replace or short some words, but I didn't do it.
Diego:
since you used the auxiliar verb "does" I guess the "formal" sentence should be used as a whole.
I mean, either you say formally:
Does anybody/anyone want to talk?
or, informally:
Anybody wanna talk?
Mixing both doesn't sound like a good idea.
In fact, as you remarked, the informal way is a lot more usual in chats.