The article itself was a bit disappointing because it focused on political issues. In my opinion the strength of HN in this regard is that it is both a "sjw cesspool" and a "haven for alt-right", as evidenced by the fact that a comment on a controversial topic can easily float near zero points while raking in both upvotes and downvotes. And even those who refer to it as "the orange site" still come back and comment. In other words, HN may be an echo chamber but it is a pretty big one with a lot of voices in it.
both and neither. Partisan discussions, or even any kind of bitching at all ... are outright discouraged. I often step out of line in this regard and don't always agree, but I'm also confident that folk on "the other side" face the same kind of treatment. Though frustrating at times, I respect that it keeps things clean and helps cut out a lot of nonsense, of which the Internet has no shortage should I feel the need to go find some.
EDIT - actually upon some reflection I think that I would have to respectfully disagree, and change my opening sentence here to just "neither". Extremes of opinion that are "off topic" are not tolerated, and this is a good thing.
People who show up for political debate generally do so with knives drawn; you hear from the loudest people with the most solidified views, and the stuff that rises to the top is playing to the crowd instead of engaging in extended discussions. But in a rec sports team, a movie club, or a tech forum, people aren't grouped by viewpoint and vitriolic arguments are a distraction from the original cause. So those places seem to breed conversations where people take the time to hear one another and avoid breaking down into pure tribalism.