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.