Earlier quoted context omitted.
HN is text based, so it might have a bias towards people who like text.
Agreed. The community is probably biased towards people who are (1) a little bit smarter than average, and so relatively happy to go away and learn things by themselves, and (2) generally more interested in maths, technology and science, which lends itself a little bit more to just "working through the problem sheet" as opposed to, say, the arts and humanities.
[citation needed]
I agree that on average we're much more willing to learn things ourselves and interested in the subjects you listed, but I reject the idea that the community prefers text content because we're smarter than average. One problem with HN being connected to YC (though it comes with a lot of upsides) is that people will always go out of their way to appear smart. Everyone knows that can help their chances of getting accepted.
Sure, literally everyone that has replied to my original comment has said they're in favor of learning by reading plain text, but the fact is less HN users would have followed along with Sam Altman's "How to Start a Startup" course had it been in that format.