I don't blame people for going for the easy money, but it's like paying "writers" to write thousands of articles about "best pool equipment 2021" to target keywords on Google just so you can soak up Amazon affiliate revenue. Sure you make money, but how many people are reading your "blog" as fact?
These sites aren’t going to to really test the pool cleaning equipment, the web hosting services being reviewed and ranked, learning Python tutorials. Nobody is going to pay anyone to test anything to make sure how the how-to cobbled together from three similar articles actually works.
I'm not the only one doing this, of course. Most of the books I see my competitors make are of lower quality, but they probably paid a lot less for them. In general, books made by people like me read like really long blog posts - because that's where most of the information comes from.