I have hundreds of pdfs of books, and a thousand dollar library (my friends call it) We have to keep this stuff. This isn't the first time we've lost our books. It happens every 80 or so years
Because legally then it's a copy and not a format conversion.
This story has a lot of details left out and is a magnet for illinformed commentators: the reason the originals are destroyed is because it is legal to do so for the purposes of format conversion, but not legal to retain the originals under copyright law.