Don’t think that’s quite true. It’s continuation of the old “something you know”, “something you have” and “something you are” authentication factors, and the idea that at least two factors should be used to authenticate.
The username/password approach is only a single factor, “something you know”.
Common 2FA solutions use “something you know” (you’re password) and “something you have” (a device proven via OTP or SMS).
FIDO with biometrics trades all that for 2FA driven by “something you are” (biometrics) and “something you have” (you’re devices Secure Enclave).
You don’t send you biometrics to the service your authenticating with. Rather you’re using your biometrics to prove “something you are” to your device, which your device then mixes with a private key which proves you’re in possession of a known device. All of that is then used to authenticate with your service.
In order to enable a cloud synced private key, you need the syncing process to require 2FA to enable new devices. The 2FA process can be clunky and slow, because you only need to do once per device enrolment. Indeed it’s need to be clunkier, because you don’t have a biometric factor available for use, as the enrolment process is normally used to onboard both a device and a device specific biometric factor.
After that you’re device becomes a know authenticated device, which can be used as “something you have” factor for authentication.
All of this isn’t a change from long standing authentication strategy. It’s just a refinement of process to make the underlying authentication strategy user friendly.