there are already dozens of good stand alone forum products. there would be no need to use a purposefully federating platform where half the code is put to federation. silly.
twitter/mastodon is just an old man shouting into the cloud (single to many). the discussion is very limited in scope. forums (many to many) are much more intensive due to the volume of human activity and its nested interactions with said data.
even if you just look at the biggest players thats dozens of servers with 100k users all upvoting/replying/moderating and your instance needs to process that if you want a decent interaction.
threaded-discussion server products require far more resources than a simple mastodon, twitter like server. if you want to federate with the threadiverse its going to be resource intensive.