Another player is entering this debate and is represented by holistic practitioners. The theory is that trauma (wide definition) impacts the body at the cellular level, and is not limited to just the brain. Psychology and Psychiatry deal with the brain, but the holistic practitioner deals with the entire body. If in fact trauma impacts the entire body, then depression is not limited to the brain. Unfortunately, this field of science is in its infancy and is not given any credibility by medical science, which likes to compartmentalize things.
The clinical psych folks want you to keep coming in for therapy at what, a hundred bucks a visit, once to three times a week for years.
Pharmaceutical interventions are a helluva lot cheaper. Most people I have know who have tried both prefer the medication.