Your signal: I don't care enough about our communication to use WhatsApp, because of reasons that are obscure to 99% outside a tech community. Similarly, they don't bother to reach out to you on other communication channels, because they don't bother enough.
The important thing to understand is, from your communication partners point of view, you create a burden without reason, so they work around it in (their) most effective way.
I've been there and didn't support this or that messenger. By now I think, the only way to solve those kind of issues are i) sane laws that regulate privacy and communication security, and ii) trends that create a need for a new communication style - private, secure, and human (like, calling from time to time, find a better solution to ghosting, things like that).
I'm convinced that we need positive incentives for that, instead of creating artificial burden.