People who are more tech libertarian don't like when critical aspects of their life requires a smart phone from either Apple or Google. The ability to avoid these companies is becoming increasingly difficult, and attestation is one piece of that puzzle.

I don't think that means throwing out passkeys entirely, but that's why you're seeing a lot of "slippery slope" stuff in here

Well those people can buy a YubiKey for $30 I guess. I don't see why that's a big issue.