People who actually read a lot. The ability to absorb information-dense content like this is a skill that comes with practice, just like math, programming, music, or anything else. The more you do it, the better you get at it.
Learning some speed-reading a few years ago really helped me personally too, the drills they provide help improve concentration and focus. I'm not an expert, but Evelyn Wood's books are a good start imho.
Any thoughts on the actual content of the article rather than the presentation style? Or is it the lack of a neatly packaged conclusion that throws you off? It seems like a perfectly readable exposition to me, even if I don't necessarily agree with author's points.
It's hard to have thoughts on the content, as it's basically a novela of random things tangentially relating to self-imposed isolation. I would be here all day.