Earlier quoted context omitted.
You've never seen a paperback made in the 1960s-1990s? The paper is brittle and the pages are literally falling apart. You can't read paper where pieces of it have fallen off and disintegrated.
I have many paperbacks from the 1950s to the present day. Some of the really old ones are a little yellow around the edges, but brittle and falling apart? Never. I have no idea what you are talking about.
No problems with small books of reasonable lengths. At some point the number of pages in the popular books exceeded the durability of the cheap binding tech in use.