That's a good question (and the downvotes are unjustified), but > you'll never convert the majority of your friends/connections to use these niche messaging se

That's a good question (and the downvotes are unjustified), but > you'll never convert the majority of your friends/connections to use these niche messaging services isn't true -- it's certainly possible, if you are pushy and refuse other apps. I pushed most of my close contacts to use Signal and now they use that (among other tools). Unfortunately Signal is not very good, because it's not very reliable (calls fail ~40% of the time, sometimes messages don't arrive) and the engineering practices lack (almost no tests, no CI, "bug bankruptcy" closing of all issues on the bugtracker) so I don't have high hopes for reliability to improve. This made it harder to convert people, but it worked nevertheless.