In a nut shell, there are a lot of books out there, and people are relying on them less and less as search engines become the dominant way to find information. It's pretty hard to pour massive amounts of work into something when you know most people just want the code snippet that gets them past their current problem. No actual learning required.
...and then they have no idea how the code works, so cannot adapt it to new requirements, or debug it when it doesn't work.
To me, a good tutorial is worth a thousand times a code snippet - although I do find that often MS Press books (at least, of a certain vintage) will print the entire source of a sample program which leads to the new stuff being lost among the boilerplate.
How new Windows programmers are supposed to learn what's going on when truly excellent books like Jeff Richter's "Programming Applications for Windows" go out of print I don't know. All abstractions leak, and I think you're better off understanding what leaks through the abstraction.
I only really ‘got’ MFC once I’d read “MFC Internals”, and understood the boilerplate that Visual Studio generates for a new MFC project.