Biometrics are not a password, as they are not 'something you know'. Neither are they like a username, as the implementations for challenging biometrics often cannot guarantee either uniqueness or lookup capability.
They are rather one of the three classes of authentication factors, all of which have fundamental drawbacks. This is why you should always require more than a single class of factor as part of your authentication. For example, mobile devices typically require both physical possession as well as a knowledge or biometric challenge.
Leaving fingerprints on your device is why fingerprints aren't the best factor for mobile devices. Captured biometric data being snooped and replayed is why remote biometrics are weaker than biometrics done locally.
You can have a Web Authentication authenticator (e.g. FIDO 2 key) act as multiple different credentials, all unlocked with the same biometric. Biometrics being tied to a single account (or an account being tied to a single biometric) is an implementation detail, same as having only a single account per email address on a site is today.
A good portion of the revolutionizing is trying to optimize the UX, not authentication. The core fundamentals of authentication have been known for a while, to the point we have government standards such as NIST 800-63b. Of course, some of the revolutionary UX turns out to not implement the fundamentals correctly, because it's the tech industry.