For me, I know it's not genetic, because it doesn't run in my family. I'm the only person with it. I didn't have the negative experiences like you & some others with SA did, either, it was just always a part of me. I know it has to be in my brain structure (whatever) because there's no other explanation. I was verbally tortured from about first or second grade on in school, but my SA was present even as a toddler, long before that, even though there were no environmental factors creating it or making it worse. I wasn't beaten or abused in my childhood, & I'm not the only person with SA who wasn't.
Just as there is more than one "cause" for SA, there should be more than one treatment. For some, therapy is useless, for some, meds are useless. For some therapy is the only thing that helps, for some, meds are the only things that help. For some, they need both. Automatically saying that because your SA was caused by environmental factors & helped by therapy, does not mean that everyone's was caused by the same thing, or would benefit in the same way. Some people would do very well on meds. When people read posts on forums like these, it can inform what they do or don't do. So, if someone who has never sought treatment before sees those saying that meds are useless, they might not try meds & might end up forgoing their only chance at getting better. The same goes with therapy. I think that people should try both meds & therapy because you never know what might work for who.