@Ellundril depend on the magic system. Few magic system actually have it exclusively originate from the person. More commonly, magic is everywhere like the one in this series. People can utilize their own pool or use the surrounding mana with a ritual or object. Magic is also often use as an add-on like physical enhancement, or enchantment. The quote is about the end results rather than the working of the system. A sufficiently advance tech can produce result that look indistinguishable from magic. A teleport belt in sci-fi is basically the same as a teleport spell in fantasy, different mechanic sure, but same result. Plasma cannon = fireball spell.