Well, technically speaking, writing can be used for both [nearly-]ephemeral communications (letters/messages) and persistent storage (books), so literacy levels alone don't immediately imply that the knowledge is archived and distributed this way.

But your point is absolutely valid, because, I believe, every (or so) civilization that had invented writing, had books or similar concepts (tablets, etc). Persistent information storage in form of written text just can't be "western" thing. Libraries had and continue exist nearly everywhere, regardless of the culture.