I'm pretty sure that more than one study has proven placebos are as "effective" at alleviating low level pain as are pain killers. Just as an example. The placebo effect is noted in many instances of medical complaints.
So at the moment, we don't know WHY or HOW acu-puncture -pressure or traditional medicines work. Actual physical influence, or placebo effect? That's the problem, and it's the same one we encounter with dowsing, throwing stones, etc. Actual physical effect, or anecdotal cherry picking combined with some good luck and intuition based on previous experience?
Science as our society has practiced it requires theories that propose a mechanism and make predictions based on the mechanism's supposed action(s). If the predictions turn out to be true, it's then accepted that the theory is correct. In other words, we then "know how/why it works." I mean, in vastly simplified terms.
Given no one has any proposed mechanisms for dowsing/throwing that have led to predictions of results of rigorous testing, we're just all in the speculative dark!