Yes the science has a long way to go, but you're ridiculously generalizing. Some people stay on antidepressants long term, but most don't. Many psychotropics are used only short term. I think your test/cure paradigm is a bit of a "red herring"... maybe it would be nice if it were the case, but symptom (and impact) based diagnosis plus subjective improvement to symptoms, functioning and quality of life still counts to people actually suffering, as well as their families.