Because HN can't be seen to discuss the military take-over of the seat of government of one of the most powerful countries on earth. It would be unseemly. The coup will not only not be televised, it won't even be discussed.
Yes any technical subreddit averages out to the average HN thread. In some specialized subreddits like /r/AskHistorians the quality far exceeds HN because you're required to know what you're talking about to even state an opinion.
Here's an illustrative example: the thread for "LLMs aren't world models (https://yosefk.com/blog/llms-arent-world-models.html)"
HN: https://news.ycombinator.com/item?id=44854518
/r/programming: https://old.reddit.com/r/programming/comments/1mnc9qf/llms_a...
I don't see a qualitative distinction between HN and "literally a cesspool of humanity" here.
I won't belabor the point because I know it's futile and diverging far from the topic.