At the risk of being somewhat off-topic (there really should be a "tools other communities use" page but as far as I can see it does not exist yet), someone recently wrote up the discussion/moderation features of Hacker News, which IMO make an interesting read.
Topic on Talk:Talk pages consultation 2019/Tools in use
@TBolliger (WMF) and @SPoore (WMF) might be interested in some of those. I believe that the ability to collapse sections of very long discussions has been mentioned by a Wikipedia editor, although I can't remember where offhand.
@Whatamidoing (WMF) en:Template:Collapse_top is super helpful, yes.