[Ulzgoroth]

I can make up a reason if one is wanted, given authorial freedom over metaphysics:

"Magical skills are only partly embedded in the material brain - essential parts are etched by training into the magic-manipulating spiritual superstructure of the self, which can't be replicated by mundane nanotechnology."

On the other hand even if you make that true, what about enchanted nanotechnology?

I can't see any reason to think the rules preclude using skill-imparting ultratech to deliver spell skills, or to think that you should necessarily respect such rules if they existed somewhere.