I have noticed this trend for a long time also, and well before this article was first written. It seems to go in waves though I'll cautiously say that it seems to have gotten somewhat better in recent years. I remember a time in the mid-2010s when these kinds of stories would disappear almost instantaneously. Now some of these articles and topics get a good number of upvotes and occasionally even substantive dialogue.
That said, the comments sections on these articles do tend to devolve pretty quickly.
Systemic reasons are why it's common to see the collective responsible for the systemic patterns in society be so fervent to deny systemic issues exist.
I myself like the idea of my success being attributed to my hard work. I would like to think that I bootstrapped my way to success. It's not an easy feeling to accept that in many ways by virtue of just being part of the main majority collective I by default have an advantage in my community over those that aren't a member in that majority collective group.
i.e. if the majority % of users in a forum are belonging to a certain category then it's reasonable to believe that most of that majority would be against anything perceived as a criticism of their group (and by extension themselves).
American's love talking about those issues. It's probably the biggest thing they love talking about compared to most other countries.