This is just not realistic, and not how the world works. "Oh, you expect me to be available on the app we used to communicate regularly and most people in our circle use? Too bad, I just dumped it and got on this new app, so you guys better install it just to have the privilege to communicate with me."
Umm, no. I use both WhatsApp and Signal (way before this hysteria began) but the "just leave" mentality isn't realistic. Most people don't care about this stuff enough to install a new app and start using it. Even for people who will join it, it takes time. The network effect is still there.
Being on HN too much and/or having social circles full of people who think like you misleads people.
None of the people I had on WhatsApp think like me. They're mostly just my family and relatives. But I told them "I'm quitting WhatsApp, if you need to message me, use Signal". And they all just downloaded Signal because it's honestly not that big of a deal. It's just another free chat app.
"It's not how the world works". Of course it is. Most people downloaded WhatsApp because someone told them to so they could message each other.
It isn't how the world works. For change there needs to a value proposition. Your entire proposition is it fits your personal views. Why do you expect others to change for your personal choices when you aren't willing to change for theirs?
You essentially have a personal disagreement with the practices of a specific company and want to inconvenience others who might not think the same way. It's arguably a selfish perspective, family members may be willing to bend to those demands for an individual. But to expect businesses to indulge every single individual preferences for how they wish to be contacted is impractical.