Re: I bet in spite of the usability angle, there is little to no fingerprint support
Your distinction between a password and an identifier is firmer than it is in reality. Theoretically, a password is also just an identifier, just one that theoretically only you have access to. A good enough fingerprint is also something that's not trivial to look up and provide, so it's also something that you have uniquely easy access to. The problem comes because it's not as easy to guarantee that nobody else has it. For something that needs harder security, that risk makes a fingerprint a bad choice. There is a reason that my fingerprint reader remains unused. If you're using a system where your password is an easily guessed string, as many people do, that password probably isn't more secure than a fingerprint.
There is nothing intrinsic about a fingerprint that prevents it from being a password, though it is prevented from being a good password. The analogy to a name is flawed. I know the names of many people, so simply asking for the user's name is not a valid password. I do not have the fingerprints of any person other than myself, so they are not useful to me as identifiers.