Hot take: the fact that HN comments have an academic/professional tone doesn't make the noise go away. It just makes it easier to pass for useful comments.
On huge threads with like 1k comments, I do find that the high quality ones float to the surface (having more to do with stuff like hiding vote counts and restricting down vote access IMO). However, it's not hard to find people confidently talking out of their ass making it to the top of threads with even hundreds of comments. Look for people talking about something you are an expert in (or do a brief google search on a topic somebody is claiming expertise in, especially if it is related to ideology) and it isn't hard to spot. There are even all the bad cliche comments of the other platforms even if they aren't as simple as "have an upvote my friend" or "username checks out".
I find threads on politics and culture particularly unbearable here because it's the exact same chest beating and narratives that you will find on any other platform except that the posters possess the same self-rightousness and academic tone as if they were talking about mathematical fact and not a political opinion. Even more so, it often comes without the self-awareness to know that your opinions and arguments are most often being taken from whatever social media you frequent. Everybody is a "free thinker" here even though they spout off the exact same political arguments as everybody else in their clique. It makes some threads pretty toxic IMO because of how seriously everyone takes themselves. I'm of course making general claims to which there are exceptions, but this is something I've seen.
Thinking that you need to be super-intelligent to post on or browse HN is a bad meme. Take the guy below me that thinks jokes on HN "require higher levels of intelligence to parse". It's the same mentality that part of the Rick and Morty fan base gets made fun of for.