This isn't true. Your light switches do not heat up to lightbulb temperature when the light is off. Heat is only dissipated when electricity is "used", more or less by definition. You seem to be describing a linear voltage regulator, which does have a load resistor and is wasteful if the step-down distance is large, but no modern electronic circuit would use such a thing in a power supply - it would use a switched-mode buck regulator instead.