But then we go deeper into what placebo is. If the patient needs the psychological comfort of being seen and OK'd by real doctors, staying home mentalizing their own well-being won't do much. It's about taking responsibility for self-care--to the extent possible, of course--as opposed to externalizing any ill state to a sanctioned (sacred?) pill.
I think placebo can be self-administered. I can make many pains decrease in intensity (or sometimes go away) just by thinking about it.
Last year I fell while mountain skiing and was in great pain at first (could barely move, standing up from lying down was excruciating, etc.)
The first day I didn't take any pain killer; the second day I did but it didn't really help. The third day I stopped taking the pills and just kind of "decided" I wouldn't suffer that much.
The pain didn't disappear completely, and it still hurt too much to get back on skis, but it stopped being so intense. When I got back home I did an x-ray exam and MRI and found I had broken a vertebra in two, that had lost 25% of its height. The doctor was super surprised I could walk normally and said: "do you not feel pain". I said I did but it was very manageable. She didn't investigate and just said "ok then, good for you!"
Also, I used to get hiccups that lasted a long time (30 minutes); and then I discovered you can make them stop very fast by being super calm and concentrating. Not only that, but since I found this out, I barely get hiccups at all anymore.
I think we can consciously control much more of our own body than we think, and we're only scratching the surface.