One potential implementation: at the top of each thread, after the metadata for the thread itself and before the comment box, are a list of ‘Related discussions’ with a bulletpoint list of related HN threads.
As someone who's worked on HN code since then, I can tell you there's no such "mindset", nor is it true that "we don't get any iteration on the feature set here" (11 days ago: https://news.ycombinator.com/item?id=25197418). It is true, though, that most of the changes are subtle enough not to be so visible, including the ones I'm working on this evening. Most of the effort goes into attempting to improve, or at least preserve, the quality of submissions and comments.