Re: Lose your device, lose your access
Theoretically correct but farraginous.
In addition, the very process of adding a passkey of sort, to an account, if possible at all, is the system weakness.
Perhaps, in future the availability of reliable biometric scanning plus some sort of predetermined changing temporary authentication factor, for instance a password changed ad hoc by an agreed method, could become the norm.
However, at the end, no method can be totally secure.