I assumed it was downvoted by people who see China as being largely a state capitalist economy with a nominally socialist/communist government, whom I would guess are primarily lefties. Contrary to seeing it as western propaganda, they'd see it as Chinese propaganda as it pretends that the country is something it really isn't.

This is only a possible view, of course.

Fully sourced means my statements were sourced, not that it was dripping in sources.

Also, the book I cited is not propaganda. Please don't resort to calling everything that posits an alternate view propaganda.

From the Springer page on the book,

Roland Boer is a professor in the School of Marxism Studies at Dalian University of Technology, Dalian, China.

So he has a degree in and is a professor in the exact subject he's talking about, from a respected University:

Dalian University of Technology (DUT) [...] is a public research university located in Dalian, Liaoning, China, with an additional campus in Panjin, Liaoning. [...] Formerly called the Dalian Institute of Technology, DUT is renowned as one of the Big Four Institutes of Technology in China. [...] As of 2022, DUT was listed as one of the top 400 global universities in several major international universities' rankings

Moreover, it's not some random publisher or some guy's PDF on the internet. It's published by Springer which, if you have done any academic reading in almost any field, you will know that Springer content is high-quality and trustworthy. In fact, at a lot of the university libraries I've been in, some subjects (maths, especially) are probably three-quarters Springer publications,

Springer Science+Business Media, commonly known as Springer, is a German multinational publishing company of books, e-books and peer-reviewed journals in science, humanities, technical and medical (STM) publishing.