I can’t help but think that the pervasively available, ad-supported* nature of social media, enabled/amplified by smartphones, has had a more massive effect on the changes observed than the almost trivial-by-comparison elections in 2008 or 2016.
There’s a good chance that much of the non-tech content on HN is tapped out on smartphones (including this comment).
* Ad-supported is a higher-order problem. Ads are not inherently a problem, but optimization for ad revenue often leads to optimization for engagement, which drags along time-wasting and optimization for outrage engagement, dunking, like-farming, etc.