Good points, and I didn't mean to say that there isn't some placebo/nocebo effect. There's lots of evidence for the connection between mind and body, so it certainly seems plausible this happens (also not a medical expert).

I've always found the placebo effect fascinating, but does seem, at least in popular coverage?, to be puffed up more when there's a lot we don't know. And of course it can be very hard to untangle when some people will just get or feel better for who knows what reason. Medical and human research can be very messy, much as the physicist in me just wants to see the hard stats showing a strong (causal) relationship.