running a smaller, continuous, current through them. PWM is done because it's cheap to implement given a fixed power rail and a digital control : need a single

running a smaller, continuous, current through them. PWM is done because it's cheap to implement given a fixed power rail and a digital control : need a single/couple of power switches that can even be integrated on die for low-ish power targets. continuous things usually need some kind of discrete filters, that means more components etc