What a scary thought! ;)
This assumes that there is a single business key that defines an anchor. Let's say Customer can be identified through either "which loyalty card was used at the time of purchase", "a personal identification number", or "a customer number". Which of these would you pick for the hash?
This also assumes that a business key cannot change over time. In Sweden, everyone has a "personal identification number", but this number is not stable over time. It may change. If you picked this number for the hash, would you then update the hash when you are informed about the change? How would you know how to connect old data to the new hash?
I agree that it would be much easier if there was one single key to rule them all, but unfortunately there is no such thing.