Moving the reviews to blockchain eliminates the problem that a traditional centralized competitor (e.g. what Zocdoc) creates. A doctor builds his reputation in the platform over a period. But if he stops paying the subscription fees, for his/her profile, the all the work over the time span is lost. All the reviews from the patients are gone in the wind. S/he basically gets tightly integrated with the centralized system. With the use of blockchain, the reviews and scores remain forever and no one can change, remove or manipulate it.