AFAIK, the "real" placebo effect is a very small and specific thing that goes on when pain alleviation or inflammation are experimental variables, because of the body's μ-opioid system.

The rest of the placebo effect, outside of that domain, is being increasingly found to be the result of under-powered experiments.

We can choose the argue about the scope of the effect (I think it goes beyond just pain and inflammation, and don't think it's limited to mu-opioids), but generally, yes, pain and inflammation are the two areas where the placebo effect has been seen to occur in a well-powered, well-controlled study.