"Monopolizing magic knowledge," Garel sighed after learning about some events in this world, "was indeed a transition, yet you failed to complete it."
In the Dragon Tribe, he was considered an elder dragon who had seen too much. In his own world, the power of magic was also monopolized, largely by the noble and Imperial families. There were non-noble mages too, but they highly valued their knowledge and wouldn't share it lightly.
After all, it wasn't easy for them to acquire this monopolized knowledge. The harder it was to obtain, the more they cherished it, and these mages were loath to see the fruits of their hard work become someone else's collection...
In such an environment, even if there were those who wished to share their knowledge, it would just end up in the hands of some ambitious individuals who would seal it off and continue the monopoly. No real dissemination was possible.