My main problem with the idea of magic where you draw transmutation circles and such is that I am certain that if they worked, I'd be able to build a PCB to cast the same spell. And now you've got a setting where your toaster works by casting tiny fireballs. Do you want that?
Which is silly because PCBs are not, in fact, sacred geometry where their very shapes effect how they work. You're thinking of IC dies: silicon does actually work like that.
@cstross that's the worst thing about being a reverse engineer in this cyberpunk magical (magipunk?) future. I usually take apart a toaster and find out they use insecure firmware update mechanisms and some stolen open source code, but now I might also find yog-sothoth.
@foone Your toaster works by casting tiny fireballs but to do that it needs roughly one ARM M3 microcontroller per square mm of exposed heating element surface and some utter arsewipe will upload a cryptominer to root it via zigbee and then later a different griefer will rootkit the mining software and there'll be a bug that turns it into a soul stealer and by the way your cat is now possessed by an eldritch horror from the universe next door