Often (at least for me) the first sub-thread is not about the article but about some loosely related topic or personal factoid. The second sub-thread (for me)

Often (at least for me) the first sub-thread is not about the article but about some loosely related topic or personal factoid. The second sub-thread (for me) is often much more interesting. I also observed that it looks like there are two "waves" of commentators, the first one has a pack mentality, if they don't like what they see they downvote instead of discussing. The second "wave" often upvote what was previously downvoted (and it helps that an algorithm removes the downflag button past a few days).