The difference is the ability to privilege a medical establishment that is in control of the clinical setting. Doctors don't like competition. There's really nothing inherently better about randomized control trials as a way of knowing; that's why it is wrong so often.

In my experience body workers outside the medical establishment (like massage therapists for example) have a lot of ad-hoc knowledge about the body and its ailments from years of observation of their patients.

This kind of knowledge is actually a lot like most of the real knowledge employed by doctors - the knowledge of the hands and lived experience rather than some study in a journal.