Not only do you get the same issue with SMS authentication (have to set it up again when you get a new number), but on top of it SMS auth is not as readily available and has proprietary requirements (namely, you have to have a mobile number with text support, it has to be available at your current location, it may cost money, the auth service has to support whichever country code you're under, ...).
Also, as other people mentioned, it's technically possible to back up your initial seed.
SMS auth is a disgrace, when we have 2fa standards.
