SMS is:
1. not controlled by a single company
2. a different network than the internet
3. a fail safe for people who don't use apps or are unable to at a given time for some reason (inc 2fa)
4. a fail safe for a "small group of people" who are suffering the consequences of a natural disaster.
Though perhaps not economically feasible for certain companies, supporting redunancy is as much an honorable goal as privacy.
Is this the comment you would give when someone says they intend to take a notebook with them when travelling in addition to their phone?