Signal is not mainstream. And you can't verify that Whatsapp/Allo have implemented the whisper protocol the way they claim to. We are being asked to "just trust them".
I have had success with getting lots of people on it. And the key selling point that it is no more difficult than WhatsApp makes that possible.
And that "no more" is really important. "Just slightly more" won't do. Especially not if it's "slightly more to someone who frequents HN". Because that's likely already prohibitive to most.
Take a person that just barely knows how to operate the play store. I can instruct that person over phone how to start chatting with me securely in a minute or two:
Go to the play store, download signal, open signal, I'm already there in your contact list. Write me a message. Done.
That's an amazing achievement. The much maligned fact that phone numbers are used as identifiers is key to that experience, too, because my phone number already is on that persons phone.
And yeah, I can't verify Whatsapp, but I still trust that Moxie et.al. have checked their implementation. Still that's why I push people to switch to Signal rather than stay on WhatsApp. Doubly so as WhatsApp belongs to Facebook now (I loved their original 1 Dollar a year business model, and if they still had that I would trust them a lot more).
Even with doubts about Facebook, it almost certainly is a massive win that WhatsApp implemented this. It makes WhatsApp immune to being subpoenaed for conversations, and thus they have a clear motive to implement it properly, too.
