Earlier quoted context omitted.
It's precisely the fact that Moxie is so credible on this topic that makes his post so frustrating. I believe that he's telling the truth as he sees it, and I believe that he's as well-situated as anyone could be to pull off a white-hat secure messaging system, so if he says it can't be done with federation, it's awfully hard for me to assert that he's wrong. The problem is that I don't see the point of doing any of…
The fact that Signal exists, and I can use it every day with friends and coworkers, is evidence that we are not locked in. No one is making money from Signal, and anyone who uses Signal can switch to any of ten different (less secure) apps in five minutes. And if Signal goes away or whatever, we can build our own! The only thing stopping us is that we are a lot worse at designing crypto than Moxie and Trevor ;)
LibreSignal folks are willing to do the work for removing that dependency on GCM but Signal won't federate with them.
OTOH, moxie does have a point. They've tried federation with Cyanogen and the experience was painful.