That only solves half of the problem though. Since many people do not use password managers (and thus potentially reuse their passwords, there's still an incentive to obtain stored password hashes. With passkeys, the public keys stored in any given provider's database are useless—so any provider switching to Passkeys rids themselves of a big attack vector. Just think about a possible feature without rainbow tables, large credential leaks, and so on. That's what Passkeys enable.