Technically true. But practically speaking, I'd wager political topics lead to emotionally charged, intellectually devoid arguments (much) more commonly than others. If that's true, then this moderation should boost the general quality of HN comments and topics, which is why most of us come here in the first place. As a comparison, I was initially annoyed that simple jokes / witty remarks that were void of other content were down voted on HN. But long-term I compare it to reddit and agree with the method: I can still go to reddit if I want wit (I often do). I (ideally) come here for high quality technical content.
This may be partly because so many thoughtless people feel qualified to enter a political discussion (e.g., about basic income, or immigration), whereas they couldn't even pretend to understand real-time operating systems or functional programming enough to have an opinion.
Part of the beauty of HN is getting opinions about things that matter in the real world, from people who really think about things.
This is true, but I suspect the biggest reason is that politics is more prone to Crony Beliefs ( http://www.meltingasphalt.com/crony-beliefs/ ) than almost any other field of discussion.
You jumped to conclusion about what "matter in real world" actually means that wasn't in the comment.
There's a severe danger that you would lose. For a commentary on emotionally charged and intellectually devoid arguments about a technical subject, I give you http://uselessd.darknedgy.net/ProSystemdAntiSystemd/ (discussed at https://news.ycombinator.com/item?id=8488235).
But that's not the whole of it, by a long chalk. There have been "the OS Wars", "the editor wars", "the archiver wars", and others. One particularly extreme example that I personally encountered was a group of people in comp.os.os2.advocacy . They did all of the petty and stupid Usenet tricks such as rudely and impatiently splitting paragraphs and sentences to reply to all of the individual words. Much of the level of "argument" was the sort of thing that I'd expect from six-year-olds in a playground: parroting, insults, and general childishness.
I didn't read the newsgroup for the better part of a decade. When I went back to look at it I was astounded to see that the group was still at it, in (as far as I could tell) the same threads with exactly the same content-free taunting and rubbish.
Going back to that newsgroup again today, and picking stuff at random, here's an example of this sort of discourse. From 2011!
Here's a comparison thread randomly selected from the 1990s.