Moreover, did you ever try to port Authenticator data from one device to another? There are rumors it's possible. I work in the industry since forever, if anybody can be called qualified for such simple task, it's me. I gave up, too much trouble. Imagining that a regular person would even think about getting into these woods is laughable.

Sure Google allows you to port authenticator data with an easy 5-step process. Almost nobody else does even this.

Without portability, it means losing access to your Facebook, Instagram and Pokemon Go when you change your device? People would revolt if you do that.

So what's the alternative? We either use SMS, or we use email (which will have like order of magnitude higher failure rate with no added security) or we don't use 2FA at all. Or we think really hard and invent better 2FA than SMS that works on every mobile device and is simple for the user. Then we can deprecate SMS.