Some areas of reddit do similar things with similar results. AskHistorians and AskScience are the first two to come to mind.

This may be a lot easier in places where there's an explicit point to discussion beyond the discussion itself - StackOverflow is another non-Reddit example. It's easier to tell people their behavior is unconstructive when it's clearly not contributing to the goal. HN's thing may just be to declare a particular type of conversation to be the goal.

I think that has far more to do with this site being relatively low-traffic. Double the traffic, while keeping the exact same rules and topic, and it would become unreadable. It's easy to "moderate" when people clearly break the rules; but "moderation" can't do anything if the only problem is that most comments are uninsightful. Large numbers always ruin things, in real life or online. You can see that on this very website on Musk-related stories, with a terrible heat-to-light ratio in the comments.

It's controversial, but if the average IQ was 120 rather than 100, I doubt you'd have 1/10th as many issues on massively popular social media; most of the moderation issues would go away. The problem comes from the bottom-up, and can't be fixed from the top down.