Something's missing from #Briar, something like a global feed of blog posts from users inside the app.
Something like what happens here at #Mastodon or #Scuttlebutt. Imagine you had to find Mastodon users on other platforms and add their contacts manually to follow their posts.
Than the fact that you can't make calls over Briar makes it even least of an option for users of ex. #XMPP.
Yeah I know there's many challenges to make that happen, I'm just saying what would make Briar take off IMHO.