The reason why I hate Discord as a replacement for forums is because I find it very hard to find whether my specific issue has already been discussed, and if I find something, it's quite hard to follow the intertwined discussions.
You're talking about a threaded-feature, I'm not familiar with that, maybe it helps. My latest experience with discord was around spring of this year, with some tokio(-rs) related projects.
But I find that something like stackoverflow or "Discussions" (not sure what the name of the app is, but many projects have them) are much more practical to use when you need to look up things.
It seems to me that with Discord, the way it works is you show up and ask your question, as opposed to searching the archives to see whether someone already asked it before.