I'm completely aware and in agreement on the sad state of the companies who manage those apps, and the transition that the various relationships have taken and are taking is from bad to better in that regard.
But I regularly talk to people from, at a quick count and including the EU as one because of the telecom rules, around 4 different countries. My circle of friends and colleagues travel frequently, as do I, and I don't want to have to think about where they are or I am before sending a message.
SMS is entirely inadequate for my usecase. It would cost me a fortune.
Those are mostly run by immoral companies that feed of your privacy.
One is bad enough, and none works for all. Except for sms.
It is not a hard choice to make.