> Because non-natural keys are unnecessary in the presence of a natural key, and unnecessary things bring in complexity. None of the things you've presented ar

> Because non-natural keys are unnecessary in the presence of a natural key, and unnecessary things bring in complexity. None of the things you've presented are actually "natural" keys, they are pieces of information that you've made assumptions about to shoehorn them into being usable as a "natural key". > Use secure channels… No channel is perfectly secure. As channels become more secure, they become harder to use and add complexity. The more places you store customer data, the more risk you create. The attempt to force semantic data to serve as "natural key" has now added risk and complexity to your entire communication infrastructure.