Actually, there are ways to work around such user mistakes in software. You could ask for 2FA code confirmation before removing a backup phone. Or you could d

Actually, there are ways to work around such user mistakes in software. You could ask for 2FA code confirmation before removing a backup phone. Or you could decline removing the only backup phone available, requiring at least one backup phone on file. Users always screw up, it's software's (developer's) job to deal with it.