While chatting with people at Hydra, a couple mentioned that they don’t use Diatribe much because they’re mobile-based, and they don’t have an app (and specifically, an app that tells them that they have new notifications like Facebook does). I can see that Discourse has an app in both Android and iOS, though I’m not sure if it does everything people want it too. Wikipedia also says that there’s an unofficial app which allows Discourse boards to make a self-branded app (so people could have a “Diatribe” app on their phones).
I’m not a mobile user, but if someone wants to install one of these, have a play, and tell people how to set them up, that might be good.