I'm still using _mylanguage_ programming forums and they're way better than Reddit / HN in terms of an actual discussion becaues those two (HN/Reddit) are more like "move fast", so topics "disappear" from front page within hours instead of days. Ofc forum with _huge_ community will move fast too, but often things are divided into subforums, so it at least attempts to prevent that

So, when it comes to an actual, long arguing instead of upvotes wars then forums are still unparalleled.

Also having mentally stable moderators that have strong merits and community that understands fallacies helps a lot.