I think you're both right, in that each other's approach is not looking at the full picture. Depression is a physical disease; it requires physical treatment (medication, diet, and exercise: choose 3). But it is a physical disease that is deeply challenging psychologically, and unhealthy coping mechanisms can cause lasting damage. It would be irresponsible to offer only physical treatment without at least assessing whether the patient needs help dealing with and repairing the psychological effects. And what do you know, integrate the two extreme points of view and we've arrived at basically what doctors are doing now. Maybe the medical profession aren't all idiots after all.
I do think you can say that about any disease, not just those in the nebulous psychosomatic category. All major disease cause lifestyle disruption and can certainly require talk therapy after/during (although I firmly believe love, attention and care from family or friends is much better).