I don't think so, HN has a pretty specific audience. Just like reddit opinions that don't follow groupthink are often downvoted.
If the single board were about relationship advice, some identity politics subject, video games, or some pornographic theme, the quality would drop similarly.
Reddit's r/programming is, for instance, not all too bad but r/linux is a disaster, for it is quite close to identity politics.
It also just depends on your subject of interest and what tone of voice, humor, etc your are appreciative of.
My point is that HN is lucky that it is small and focuses on a particular topic of discussion and therefore it is quality over quantity. Reddit is a beast and allows discussion around really anything that pleases people. But it is a victim of its size and really reflects problems with other social media platforms such as FB and Instagram where rigorous moderation is next to impossible at that scale at the moment.
Think of /r/Wallstreetbets as an example, a subreddit that went from around 2.5 Million subscribers to 8.8 Million subscribers in a week. How do you appropriately scale moderation to content like that.
If HN grew significantly and wanted to enable more diverse conversation, it would essentially turn into a Reddit.
The more niche a community is the higher the bar to entry the less internet riff raff you get. The more one's past comments stick around the less inclined people are to type bullshit. Reddit is slightly better on average than 4Chan. HN is better at the extremes and on average than Reddit. But they're all crap compared to some niche forum you've never heard of where the guys who maintain diesel electric locomotives (or some other niche) hang out.
You could basically compare HN to a single subreddit.
Reddit just doesn't tailor itself to one particular type of discussion like HN does. But rather the dominant topics of discussion such as /r/funny frequently dominate the front page due to popularity.
Reddit is really what you make of it and if you only subscribe to topics that interest you, it becomes a vastly different experience than what a default account would be subjected to.