Passkeys bother me because they depend on the availability of another device. That just won't cut it for a lot of folks, especially people that are prone to losing devices. It's also annoying to have to deal with the 50,000 places that are fighting to keep your passkeys, leading to fragmentation and uncertainty as to where these credentials are stored.

Haphazardly implementing passkeys also has big problems - one vendor I use implemented them rather badly and randomly one day, completely removing the previously-solid password/MFA setup they had, replacing it with a "you are required to confirm on your phone with no other alternative" passkey, which was really annoying. I don't like my logins messed with. Passwords/MFA, while not perfect, work very well for most people, myself included. Passkeys still feel like they are in a very immature state.