Personally I think its a great idea and something I'd actively encourage.
I don't believe it is something to be encouraged by setting up a place on the forum to do that. There are simply too many risks involved. What a better place for a predator to look than a place where vulnerable people are looking for acceptance.
There are ways round it though.
1: have a minimum post count to qualify, say, 200, just pulling a figure out of my arse. That way it demonstrates a post history and yadda yadda yadda...
2: Effective moderation. Necessitate people who are using the facility to actually divulge some personal information to the admins to provide verification. For example, adresses and such can be verified in the UK on sites like 192.com and so on.
3: Dont make the subforum acessable, or even viewable to guests. Make it viewable to people when they hit the postcount target.
4: Stricter warnings/disciplinary measures for people abusing the facility.
5: Give it a dedicated moderator.
6: Enforce an 18+ madatory thing on the website for the sake of child protection and all such.
I know its not fool proof, but that would go some way to limiting abuse.