Ah, MSH, let me put it in clearer terms. High School did more damage to me than it did benefit, on pretty much every level. Academically, I got worse. Socially, I got worse. Psychologically, I got worse. The only social lesson I had reinforced by high school was avoidance, and that did
nothing beneficial. Pretty much every gain I've had related to what you're talking about either occurred outside of high school entirely, outside of normal classes, or after I got out -- as near as I can tell, I'd probably be notably more psychologically stable and socially able if I had avoided more of the experience. I've met a few people over the years that were literally traumatized by their experience during that period of their life (I roomed with a fellow that would wake up screaming about a fifth of the times he slept, due to certain events.).
I'd not call the high school experience a necessarily beneficial (even if unpleasant) one. It depends on a lot of variables, and I've so far seen pretty strong indication there's other venues to exploit for exposing children to the potentially beneficial aspects of that sort of education and socialization.
E: Well, being fair, it did lay the foundations for later realizing that a poorly designed and half-implemented creche system is a terribly ineffective way to manage anything useful, and that the education system in my state is pretty bloody terrible, but I'm pretty sure that's not what you're getting at