Passkeys don't need to be cracked after a data breach of your backup provider, they are just usable, right there.
> There are so many ways passkeys are superior to user-memorized passwords from a security perspective, it's laughable to call them "as insecure as a password".
Passkeys are accessible permanently on some devices unencrypted or decryptable in the filesystem, if part of e.g. a backup. Whereas passwords are usually only accessible temporarily. That makes the attack surface top copy over some passkey far larger than for sniffing a password.