The reason video is winning is because you can make a living on video advertising. It's not really possible in this day to make a living on writing, outside of specific niches. So people who are good at writing use that skill to make video scripts, not blogs or books.
Video monetizes attention better, but writing still monetizes authority better
Yup; I'd make the claim (as an internet commenter, not an expert) that audio / video is more aimed at passive entertainment, whereas reading and more importantly deep comprehension etc takes more effort and time, and it's harder to monetize.
Not impossible, mind - the author posted this on Substack which is a way that one can monetize writing (blogpost style articles anyway).