There's nothing deceptive or sneaky about it. There's value in distilling information from a bloated book down to its useful ideas.
There are lots of books that are just existing ideas repackaged for a different audience. For example, Atomic Habits is basically a repackaged version of BJ Fogg's research papers. And people see value in that, so why isn't it okay to do that in a more 1:1 way?