I'm going to disagree somewhat...I think it has _some_ to do with it. I think the UI acts as a sort of pre-filter. I think just having a list of boring looking text (like HN) draws some types of people and repels others.
It is true that HN draws some types of people and repels others, but I think it's because of the culture more than the UI. I mean, old Reddit looked almost exactly like HN and it's as mainstream as a site could be. Craigslist was even more minimalist than HN.
The left numbers almost act as a bar graph to tell you how popular something is, and it is otherwise chronological.
High text interfaces are also dense compared to modern mobile touch based interfaces trying to render on a desktop. https://signalvnoise.com/posts/1407-why-the-drudge-report-is...
I find that some of them are not highlighted even though the numbers seem high enough.
I'm sure it's an algorithm cut-off thing, but I'd like if the lighting scale was a little more linear.