One thing that's very noticeable compared to traditional forums, and I think plays into this: Traditional forums for deep topics have year-long threads where people are figuring something out together or share project logs. As long as they are active, they get pushed to the top. Reddit does not have that, and suffers for it. (HN too in some ways). Linking back to old reddit threads when continuing a topic is tedious and excludes the discussion even more, so it happens in way more limited contexts.

In contrast, "I just bought X" typically is one megathread in a forum and not half the submissions.