The Vatican couldn’t keep up with the Index of Forbidden Books which was far smaller than the number of permissable books. The problem with the Nihil Obstat / Imprimatur imprint is thgat it only says their is nothing of danger to the Faith in the book. It can be the worst “hack” writing and still make the cut. Many of todays non-religious books, which would never be examined in any case, probably represent more of a danger than any other genre. People have to educate themselves to recognize books that are dangerous to their souls.