One of the major issues they encountered is a lack of data. 34 percent of the doctors they looked into didn't have any reviews at all. That's before adding in that critical information was often missing like what language the doctor spoke, the doctor's hospital affiliation, what insurance is accepted, and specialties.
Doctors who did have reviews averaged seven in total. That's far too few to feel confident you're getting accurate information. That is especially true since many reviews are left because the patient either had a great experience or they're Morty Seinfeld and are convinced the doctor stole their wallet.
As Vocativ notes, many networks have already recognized the problem and are attempting to correct course. For instance, the University of Utah health system collects evaluations from patients and makes them publicly available. Systems similar to this where patients are surveyed is one of the potential solutions the researchers suggest. Until then, well, you probably have to keep looking for a doctor the same way you look for a quesadilla maker. Awesome?