Ah nice, I had this idea and was thinking of implementing it. This is probably a very scary idea for a lot of people, but the reality is that it's no different

Ah nice, I had this idea and was thinking of implementing it. This is probably a very scary idea for a lot of people, but the reality is that it's no different with regards to security than other approaches, but it's vastly simpler (which should be a win). I can't speak to this specific implementation, but the reality is that if your master password is leaked you have to rotate every credential no matter what.