You assume that they are “conditions” in the physical sense with a single defining cause because a psychiatrist at one point decided to award a name to a set of

You assume that they are “conditions” in the physical sense with a single defining cause because a psychiatrist at one point decided to award a name to a set of superficially similar symptoms. “back pains” is not a physical condition; there is a plethora of different physical conditions that can result into such superficially similar symptoms and this is the flaw psychiatry as a discipline is often criticized of, the assumption that an approach which assumes a defining cause necessarily has merit absent any evidence of such a defining cause.