I found that you could do the same for many business books, and had made a site to provide summaries of the books. What sparked me to do it was reading "The No Asshole Rule", which was so devoid of actual content that it could be summed up by its title. It was full of anecdotes and statistics that ended up drawing the wrong conclusion.
So I think this is true, but it is not necessarily a terrible thing. It is one thing to memorize a summary of a book. It is another to engage with and apply the ideas in the summary. The goal of a book is to hopefully give you enough time and space to do that.
Unfortunately, most of the books I've read just have the extra material as filler, and don't lead to much engagement. It was just anecdotes like "the nurses in hospital X reported that their bosses were 30% assholes, and in hospital Y they were 96% assholes, so it's no wonder hospital X saved 49% more patients!" and other non-sequiturs like that.
