Well, I don't know why Lisa Bardack is her doctor, but both of the things you cite (top medical school and patient reviews) are more or less meaningless.
Dr. Bardack may be great, or she may not. I don't know her, and I don't know anyone who does. That she's being used by a very powerful organization is at least as plausible as the inference that she's a bad doctor.
Did not say she was bad just not a well known, widely respected doctor that one might expect a snob like Hillary to see.