not even close the same thing. oauth/oidc gives too much signal to the identity providers. it's a 1990s solution at the time advertisers were writing the specs

not even close the same thing. oauth/oidc gives too much signal to the identity providers. it's a 1990s solution at the time advertisers were writing the specs alone. and the implementation required oath-nascar-sponsorship pattern to have dozen of providers. no bank would accept that. webauth is a spec of this time, were it's still owned by advendors, but with a couple device vendors now for a semblance of balance. and it also solve the implementation issue of having to show too many logos on the login page. so, no, it wasn't possible before webauth. webauth solves the oauth issues for 3rd party attestation with a semblance of anonymity (which is meaningless if both party exchange data on back channels)