Reddit/NH/Twitter/Youtube/Google all default to favoring freshness. I believe this design assumption to be a mistake.
A lot of what gets posted would be better served by some hybrid of a wiki+chatroom/forum. For example, Ill just pick a thread that gets posted every week. In the what else will I like subreddit, there is constantly a "post your best mindfuck movies". That kind of question and answer is best served by some kind of static wiki like page that allows voting on individual database entries. It is better served by someone bumping the topic, maybe creating a new chatroom for the day, having the best parts of the chat post to the forum, for archival and historical purposes. As new movies come out, they can be added to the list. Maybe filters exist that allow you to show the results only showing votes from the last year, to help rank newer entries against historical ones.
In a TV/Speaker/Hometheater subreddit, constantly "what's best" belongs in the wiki. But the wiki is some singular document fairly separate from the discussion pages. Wiki page components dont rearrange by voting. The wiki is fairly well hidden in the interface.
When some kind of funny video gets reposted, it shouldnt start a new conversation. The comments page needs a better design to combine/isolate old comments, with today's discussion.
tldr: reddit, like a lot of social media, has a deduplication problem, that they choose to ignore in favor of focusing on "engagement" where engagement is just repetition and regurgitation. social media needs to rediscover bumping instead of reposting.