Aside from needing a phone, I really don’t see the issue with SMS. For sending quick messages to people directly, is there really a better tool? You (most likely) already have a phone plan, you already have a phone, and your phone is always on you. Everyone you’re trying to contact is in the same boat, even people who are technically illiterate. All phones with phone plans support SMS, unless there’s weird plans I don’t know about.
When it comes to more complex needs (group management, e2e encryption, etc) other services are better of course. I don’t use SMS to text my group of friends, it’s really not well suited for the job.