I'm trying to answer my original question for Fedran, “why haven't mages taken over the world,” with the concepts of resonance and feedback (inspired by electromagnetic interface). As I worked through the ideas, I realized I was creating a world that didn't have one of the major staples of fantasy literature: artifacts.
Magical swords, golems, and flying castles are a significant rarity in my world because I wanted magic to be dangerous around other magic. Having a reliable tool, even something as simple as a lantern that didn't go out, was contradictory to that and also diminished the impact of the efforts that went into a Farimon Chamber.
On the other hand, I couldn't say “no magical items” because I still am creating a world where I haveand giant robots made out of wood.