Comment by xp84

It would introduce a different usability problem to have them remain truly stuck on a device, like, locked inside a Secure Enclave. Mainly that you’d have to do the setup again for every website, on every device. Buy a new phone? Back to the Stone Age. Authenticate with a password to each site on the new device, find the “add passkey” place, and install it.

I think that is a big step down from the convenience and friction level that the native password managers get you, where you save your password once and for the rest of your life, as long as you maintain fealty to Apple/Google/Microsoft, your password will always be there in autofill.