The problem with all newer systems is that they are identity based, which doesn’t scale down to all of the device/station use cases that phones exist for.
But if you start looking at those '12 users', you should notice that that the need is extreme.
This includes drug people and at-risk populations like sex workers: I'm not happy until drugs and sex work are decriminalized globally, so I want to protect sellers and buyers, a partial reason why I participate as a Tor relay admin. Then there are journalists and politicians. Apps like Signal, Wickr, Wire and Threema aren't as much the ecosystem we want as the silos we deserve.
That said, you'd be surprised how easy a sell Signal is in some cases.
I've gotten a bunch of friends over to Signal, from the likewise end-to-end encrypted Whatsapp. And after a family crisis, where a friend of the family died, I explained how the metadata of a mostly dormant Whatsapp group lighting up suddenly could be interpreted.
Facebook knows we're a family of aging parents and grown-up, mostly independent 25+ kids, so there might be a crisis or emotions whenever there are big bursts of activity. A crisis might make people more susceptible to predatory ads.
This was enough to convince my folks. So, family chats are now on Signal. The app is good enough. Granted, my parents and siblings are active in professions related to either legal or social services, so they understand the need for privacy and my overall desire to curb stomp the online tracking industry.