Well, I mean, that's not entirely true. You could orchestrate, wage, and win a Grail War, and so long as the Third Magic could, in theory, grant someone Circuits (and I suspect it could), a wish upon a seven-Servant Grail could grant everyone in the world a decent number.
But good fucking luck with that. The Einzbern have been trying for generations, and, like, sure, we make fun of their bad decisions, but ultimately plans in general are really hard to make. Your best bet would be summoning Zhuge Liang or something with your own resources, and then summoning a second Servant for the War. And even then maybe your opponent rolls Gilgamesh.
And actually, there is a route to power for people without Magic Circuits - technology. Who do you think made the Black Barrel? Who made the prototype Trismegistus, a magitech "analyzer of information" that could reach across the entire Domain of Man? Who's sitting on enough apocalyptic devices to end the world seven times over?
The Atlas Academy's practice of alchemy does not require Magic Circuits. And a skilled alchemist with the right gear can absolutely go toe-to-toe with a magus - or even, at the high end, Servants. Zepia turned himself into a phenomenon, a memetic superstorm, through alchemy, something even Tohno Shiki couldn't kill permanently. (I think. It's been a while since I played Melty Blood, and I don't think I ever beat it.)
The pretty lights all go to the magi, but the true power is, as ever, in the hands of scientists and technicians.