Why is a good question. But its usually complex enough to discourage chasing answer which is anywhere near the truth.
The ultimate answer is the Universe, simplified version takes into account only brains of people who upvoted which is also unapproachable.
So we settle for stories. Ones that are believable. Say this comment allows us to participate in the discussion without reading the article, because it has nothing to do with it. You of course open comments first, and there it is, comment about Medium (hey I know something about Medium!), which doesn't touch article - great because I have no idea what's in it.
But most whys have uninterestingly many answers. We would love to just get the "main" reason. But how do you differentiate them? Say I commented because I felt like typing but also because I have Internet access. How do you assign weights to those?
Another story reason - it's tech. We do tech. You can't escape the fact that once you have sophisticated patterns associated with something you perceive them. Ornithologist walk through the park is not the same as mine. And psychologist's social interactions are.. different.
Also, why why? How many top comments are directly related to the article and not general topic in vicinity of it? Is it enough of an outlier to be interesting or is your model wrong?
Why did I type all this.