It's an analogy that captures the essence of the problem framed in a way most people can understand it: with biometrics there is no shared secret, just a high entropy, non-revocable and very public UID.
Yes, public in a different model, with a different set of threats, but that's irrelevant to what the analogy is trying to convey.
It's a human trait to evaluate and disseminate new concepts though existing concepts. Everything is unique, if you want to refine or disprove the analogy it's not enough to call it wrong repeatedly, you need to accept that specific frame of reference is suggestive to those who chose it, and formulate your arguments from that perspective.
