Exactly! It's a fun natural development -those US breathless sales-based self-improvement books like 4-Hour Workweek, most books that Cal Newport publishes, are often blog-post level ideas inflated into a book for sales. It's only natural that people are finding ways to automatically trim the fat off to go back to the blog-level length.

"good" non-fiction like Thinking, Fast and Slow, The Selfish Gene, Structure of Scientific Revolutions etc. are books that are not easy, or even worthwhile to summarise that way. You'd lose too much information.