the problem is that the choice of messengers is decided at the beginning when you meet someone for the first time. the person is not yet a friend but they may become a friend if you can only find a way to stay in touch. for me, as the more technical person in most cases this means that i must accept their choice of messenger, because i can't babysit them to switch. (though i do have counter examples where switching worked)
i travel a lot. when i come to a new place and i need to build up connections to locals it is totally not possible to come in and dictate which messenger they should use to communicate with me. i need to use theirs. only once i gained their trust and a friendship emerges i may suggest switching to a better way to communicate. but the reality is, that if i refuse use their messenger or worse are blocked from using it then i am unable to stay in touch with people i meet.
when i moved to china i long refused to use wechat. i was unable to stay in touch with most of the people i met during that time because of that. until i gave up resisting.
There are people in my facebook feed who I haven't seen in person in over 20 years. It's nice to keep up with them and their lives and families, but if I lost access to facebook tomorrow, it wouldn't change a thing for me. I am friendly with these people but I don't actually know them anymore and am not all that invested in their lives.