Hi,
I don't know, and this will sound wild, but I think its just people who are depressed for some reason and trying to find a "home", as it were. Wikipedia makes a logical choice because you can do pretty much anything in a place with a lot of content. (I really don't think it has to do with a particular mental disability per se)
For the solution, I remember something proposed regarding -Ril-'s RfC (well, actually I think it was the one he filed against the admin) where the person proposed to have a group of 3 good editors help out -Ril- to become a better one (or something like that). I think this could be a great idea for those who want it - sort of like a wikitutor program.
More importantly, I think admins/users friendly to the person (and if there isn't one someone should step up because everyone needs someone to turn to) in trouble should try to step in and help the person more when it looks like he/she is going to get into a major conflict. This one thing I think could save a lot conflicts from escalating to a RfA, but then that's just me :).
Because I think ultimately you want to build people who can stay calm in heated situations and can think rationally (i.e. past the rules-only phase).
Sorry if that was too deep, LOL!
Ryan