Medical Record Management system using blockchain

There has been a lot of talk about using blockchain for storing medical records but I fail to understand what's the need of a distributed ledger in this case , like we can use any db which restricts updating the records for maintaining consistency, also it's more secure as it's not exposed to the public. And as far as having the data in one's control, wouldn't the hospital in case of even a small medical problem can get access to all the patients data which may not be important for the given emergency thereby posing the same risk of privacy . It makes sense in finance cause we need to verify transactions but what are we exactly verifying in case of medical records ? Can anyone explain what's the need of blockchain instead of a normal db?