I've had this same question about Christianity. So many Christians I know believe all the answers are in the Bible, and even carry it everywhere they go. But through most of Christianity, most people were illiterate. And for those who were even slightly literate, books were extremely rare before the printing press was invented.

Piggy-back question. I took a history of Japan class in undergrad, and one interesting point that the professor made was that the country had a literacy rate higher than other comparably "advanced" societies (I believe he was referring to literacy rates by the 16/17th century) due to the fact that certain sects of Buddhism either require or incentivize copying holy texts. If that is true (and it's been several years, so I might be fudging or outright incorrect)- has that practice affected more contemporary (trying not to break the 25 year rule here) level of observance/self-identified faithfulness of Japanese Buddhists?