What is your definition of "a certain age"?
As a person who has worked with collections of manuscripts and old and rare books, and have watched the digitization of materials by experts, I am all for digitization. You seem to think that the book is cut apart in order to scan it, and then it is thrown away. Far from it. If the book cannot lie flat when it is open, it is placed in a "cradle" and the digital camera or scanner is tilted to the angle of the open book. The page looks as if it is lying flat. The image and text are as clear on the scan as in the original book. The book is not disbound or mutilated.
Digitization preserves the original book. Researchers don't touch the original. Even clean hands have body oils that mark the pages. Old paper is weak - especially maps and foldouts. A digital image does not have to be unfolded and folded. A researcher does not have to travel miles to view a fragile or rare book if the contents of the book is digitized and available to be viewed on his computer. The contents, the font style, all that makes a book a book except for the fabric of the cover and the "feel" of the paper is there, just as it was when the page was taken from the press. Even better. Some programs enlarge the scanned image, so that those with vision problems can read it easily.
The original has to have special care, and even then it is deteriorating with time. It's not vandalism or destruction to save the contents in another form.