Hypothesizing aside, there are some interesting options out there like Tightknit and (for Discord) AnswerOverflow. I still think that Slack makes it way too hard to spin up and start up a community- I think there are many Slacks like the CNCF's one that would be nice as a browsable index of content.

As such, Railway's been investing in our own forums for this reason http://help.railway.com/ because we've noticed the decline of forum culture - and we want to bring it back. (Async, well thought out responses)

Maybe this is the next step of that integration!