A high percentage of IT, software engineering, and professional advice on HN is very valuable, but the percentage of other kinds of commentary that's valuable is much lower. I occasionally also get sucked into the sorts of debates that I just shat on, but most of the time I find myself having to scroll past huge chunks of comment sections because half the sub-threads are pedantic political debates over some term or whatever, nested 10+ levels deep.
To be fair, we can expect some diversity among several millions of readers from many different countries, points of view and experience in different fields.
If HN had some concept of subreddits, even if it were just a few them, the situation might be different. There are quite a few high-quality subreddits out there with a lot of experts. (I don't know if creating "sub-HNs" is a good idea in general; probably not.)