I can't believe that in 2017 we're still discussing what's wrong with our chat software. I have to wonder when we will finally see chat as a solved problem.
The OP isn't actually discussing chat as an unsolved problem. OP is arguing that chat is the wrong choice of solution to the problem of open source software project communication, because it's synchronous.
Or to abuse a metaphor, OP is arguing we need to use boats instead of cars to ship heavy things overseas, not that cars are an unsolved problem.
OP is arguing we should use boats for everything, including sending something across town. Realtime chat works a lot better for certain things, like troubleshooting, where having to wait around for a forum/email response may not be the best way of doing things.
