I don't think the DSM isn't based on cause-effect mechanisms. It's saying that the causes are either environmental, genetic or cognitive. If they're not based on causality, then no treatment would be possible and everything would be pointless. That's why clinical psychologists try to cure DSM disorders by cognitive-behavioral therapy. If we could find out the genetic or neurological causes, then we can cure them that way.
The problem with Socionics and other "personality theories" is that it just says that the current observation will stay the same and will always remain the same in the future. So if you're this way, then you will always remain the same, no matter what. There are no causes, no nothing. You are forever that way, apparently.
If you're going to say something like "Duals cure diseases", then that's just correlation, not causation. There's no explanation for the mechanism of why and how should duals cure diseases.