Asheron’s Call had (technically has) in-game paper you could write on. You could get a single sheet or an entire book. This may sound weird to the modern MMO player, but it was important at the time.
RPers, lore-hounds, and fan fiction writers would write stories in them. Some might exist in a single copy, or amateur scriveners might copy from one book to another. There was a library near Hebian-To (and elsewhere, but Hebian-To was the active spot I knew on Morningthaw) where people would gather to read the official in-game stories or share their own. There was not such a thing as a bookshelf where you could contribute player-written lore, but people might drop books for others to find or stand about as librarians/booksellers.
Beyond RP, books were extremely useful because Asheron’s Call came out in 1999. In 1999 you did not have wikis, extensive spoiler sites, or even a second monitor to refer to while playing on the other. Even if you had a second monitor, as the previous sentence suggests, finding info was a different matter; Google was still a new thing at the time, founded in 1998. Having a book of locations and directions was really helpful, and getting a book of location coordinates from a
guild leader patron was a huge boon for a new player.
Sometimes it does not feel that long ago, and sometimes I remember that some of our readers have never known a world without MMOs.