I think you are wildly overstating the value of a comments section. As a counter example, take Breitbart. Purely one sided posts with thousands of comments. And yet all those comments do nothing to change the one sided nature of Breitbart.
I find Breitbart's comments interesting, it's pretty much an outlet for people who are discouraged from voicing their opinion in standard news outlets. Though I don't go there on purpose... in the same way as I rarely visit The Guardian.
I used to run sites for years and to me, removing the ability to comment or purposely hiding it is a sign of a publication that's failing its readership.
That's true, but that's probably due to the highly polarised content of niche political sites.
What I am saying applies to sites that attract a mixture of people with different politics, gender, age, class, skills, etc. There are many different kinds of people that read the Guardian, and I'd bet that very few of those that disagree are actually 'trolls' - they're just people with different perspectives and experiences to the main audience.
On sites such as the Guardian and Hacker News you can often find an opposing viewpoint to the main article - just like you provided here.
