Jealous Hoarding of Magic Spells
7 Myths Everyone Believes About Druids suggests that druids should be fractious.
Dojo Storming is but one example showing that martial artists are violently rivalrous about their skills, masters, and/or schools.
So, too, should magicians because it would be an identical situation. Spells are analogous to martial art maneuvers: most are common but advanced ones are secrets known to perhaps only a single master and her disciple. How shall all other magicians in the world learn such secrets? By force, most likely. Jack Vance’s Dying Earth series—a major influence on Dungeons & Dragons’ magic system—depicts all wizards as jealous hoarders of the hundred spells left in that world.
Xenograg’s homeworld of Panadus has not yet advanced to where schools—of any kind—are common. Indeed, the Imperial School founded by Demograg was part of his sorcerous revolution. The three masters that coexisted as the Veler Magi were unique; likewise their College where the sum of their knowledge was taught.
Xenograg is the only person to ever be a student of both those schools. That fact predates this retrospective but this is not a retcon. The old and this new dovetail nicely. The original narrative portrayed Maret, the last Veler Magi, as very wise and peaceful. Amazingly, it is Maret who invites Xenograg into the College. Xenograg did not seek it; would have believed it impossible. To his mind, Xenograg would have had to “storm” the College to get the spells within.
Now there is a “What If…?”
Addendum: I neglected to include the witches coven. Either through temperament or necessity, female magic wielders are often depicted as working together in small groups.