@cstross Try to imagine software development without the internet.
Sure, it's magic, you can give the rock anxiety, but you have to move the rock. You have to write down the instructions on vellum; you have to transport the instructions with the rock. You can't ask anyone any questions without either sending them a letter or standing next to them to talk.
Peasants don't use magic because they can't afford it; the Moore's Law cost collapse doesn't happen.