I literally cannot understand how anyone thought intermixing related questions and answers together is in any way useful or beneficial to their users, especially when the default is set to ON.
Even Reddit has linkability to detect the URL and show you an 'other discussions' lens (for Old Reddit).
Granted, this is a slight taxonomy difference of 'other discussions' of the same exact topic, vs other discussions related to your topic. But I think it's a useful and helpful feature.
The link upthread isn't a good example, because the question is so basic it's easy for them to have a lot of related (duplicate) questions and answers. When the topic requires more nuance or is more specific, then the related questions and answers really aren't related at all, and they just add a bunch of useless noise.
hackere news isn't a question / answer site. I don't come here with the same expectations that I do when I go to something like stack overflow or quora.
Ironically, if I do a google search for something and ycombinator comes up in the results, the link is directly to the comment that is relevant- not to the top level of the article with all of the related sibling comments. If anything, from that perspective hacker news is actually a better question and answer site than quora.
So you look for a question, and all the answers are not even relevant, and often completely off topic or wrong.
I can understand the rabbit hole thing. Never thought about that. That they think of themselves as TikTok and not stack overflow or Reddit.