The quality of actual technical discussion on HN is not much better on average than any programming or technical subreddit in my experience, if they are well moderated. It shouldn't be surprising that the most technically adept people here also tend to post the least often.

The biggest difference is HN is strongly anti-humor, primarily because of the weird pathology the culture here has about Reddit and appearing "mainstream." But the lack of memes here doesn't make the rest of the content better, rather it tends to result in aggression, knee-jerk contrarianism and overconfident assertions in ignorance becoming low effort virtue signals instead.

HN is just barebones. I don’t think there’s anything about it that specifically makes it better than anything else other than tech articles float to the top.