You're not getting my point though.

  > A passkey synced using iCloud or Google account does not break that model

Yes, yes it does. Have you seen how hard it is to recover these accounts? There's not uncommon HN posts that do get these solved, but only then by high visibility. A method most people do not have available to them.

  > Or the equivalent to finding a locksmith is to log in with a non-passkey method

Sure, it is just that the backup methods end up undermining the security key.

Both of these were mentioned in my post you originally responded to: https://news.ycombinator.com/item?id=43988957