Earlier quoted context omitted.
My advice would be Xmpp with OMEMO encryption. On mobile, you can get the Conversations App for Android via Fdroid (no google play!), for the iPhone there is Chatsecure and on the Desktop you can use Gajim. The advantage over Signal would be that 1.) you don't have to share your telephone number and 2.) you don't rely on a single service provider/accounts are decentralized (there are various services for free and pai…
I didn't downvote you, but I imagine the counterpoint goes something like "The advantage of Signal over your solution is that more than 3% of the population can set it up".
https://www.jabber.de/clients/android-ios/conversations-guid...
But I agree: it should be even simpler to set up.