Even if this is true now (which it isn't entirely), that is no guarantee that it will be true in the future. Any time you use an external value as a key, you ru

Even if this is true now (which it isn't entirely), that is no guarantee that it will be true in the future. Any time you use an external value as a key, you run the risk of a policy change. An internally generated artificial key is the only safe way to ensure immutability and lack of semantic content.