Yeah, I personally know a couple people where self-research found the correct diagnosis, and I am one of them. We had a fantastic primary, who worked with us quite closely and did a lot of research after we found some new information from him.

Doctors don't know everything and don't have access to everything, they are just quite a lot better than the alternatives in the vast majority of cases, so your default odds are much better following their recommendation than anything else. Training is worth a lot, and everyone also knows it's not perfect, and that's entirely fine.