Abundance of reading material? You know, the thing that directly correlates with the literacy of a society. The reason why you can directly trace jumps in literacy rate to innovations in the easy of producing reading material.
Like if you want to pretend that the Stormwind people who learn to fight in and around an abbey where many of the rooms are stuffed full of bookshelves, and the Echo Isles people who learn to fight in and around... maybe a few scrolls? are going to have similar levels of literacy in their two societies, be my guest. But that completely defies all logic.
No, I'm going off their technological level and the importance placed on things in their society. Ancient Troll civilizations spent their time worshipping Loa, perfecting rituals, conquering and eating each other, and honing their abilities with voodoo, not stealing maths and sciences from a better, older civilization that had fallen on hard times and innovating infrastructure and political conventions.
I'll bite though. Do you want to look up the literacy rate for Rome?
Or Italy in the renaissance? Or England in the Industrial Revolution?