I have mine on my keyring. Not sure what the big problem is there.
The bigger issue with yubikeys is that you need more than one in case you lose one. And most sites only allow one passkey per account because all the mobile implementations can sync the private key. Yubikeys can't and that's actually a good thing because it makes them unique and eliminates the whole sync mechanism as an attack plane.
> And most sites only allow one passkey per account because all the mobile implementations can sync the private key.
Even when/if sites do allow multipe passkeys per account, the fundamental contradiction remains: Your backup key(s) are supposed to be kept somewhere secure where they won't get lost, stolen or destroyed, which ideally means some sort of off-site backup (at your bank or whereever), but at the same time every time you register for a new service you do need to register all your backup keys, too.
True. That is a problem. Especially because with Webauthn you can't just enrol a public key. It's one of the reasons I like openpgp for authentication e.g. over SSH. I can just give it a list of public keys to accept without having all those keys actually to hand.
The bigger issue with yubikeys is that you need more than one in case you lose one. And most sites only allow one passkey per account because all the mobile implementations can sync the private key. Yubikeys can't and that's actually a good thing because it makes them unique and eliminates the whole sync mechanism as an attack plane.