[seszett]

I happened because the phone operators made SMS a paid feature, while Whatsapp over wifi was free. Then the people for whom SMS was not free started using Whatsapp (or Messenger or other apps) and eventually those who used to use SMS switched to the same apps because their contacts were using them.

In some places the switch to these apps took longer (like France, because SMS had been free for a long time) but there is a fundamental asymmetry since SMS is free only for part of the users (so the others will never use it) while the apps are free for everyone. In the end, everyone ends up mostly using these apps.