That's because people don't understand how books are made.

They were printed on a long paper then folded onto itself which creates the pages and then stitched in the middle, the folds are then are cut on the sides to free the pages.

Books today are usually precut and then glued, I did however encounter a few books with the odd uncut page usually texts books.

Other than that page turners were and are used for high value books and in some cases sacred books to avoid damage (or if touching the book is taboo) Jewish synagogues for example use a "pointer" to read from the scroll it self because those scrolls are usually to valuable to touch. https://en.wikipedia.org/wiki/Yad