Starting a thread on your first post is kind of like walking into a room of complete strangers deep in conversation and then trying to change the subject. You only do it if you are rude, narcissistic, socially awkward, or selling something. A more socially aware person would scope out the lay of the land and make some contributions to existing conversations before steering things their way.
As far as intro threads go, I just think that people who start them are probably not going to fit in too well around here. It makes me think that the intro-thread posters probably haven't been lurking too long. This board isn't really a "Hi, nice to meet you, Bob!" kind of place.