Edit:
Oh yeah, I can also share SSH keys with friends and co-workers. I can freely choose which SSH key to use when authenticating and I can have an arbitrary number of SSH keys for a given server on each machine. Some of this stuff is esoteric, but some is not. Most of the stuff I can do with SSH keys I can also do with passwords but not with passkeys (or at least not always). Finally, as many others have mentioned, the attestation stuff is really ugly and takes control away from the user entirely.