Your friend likely was referring to the steady-state power drawn by a load. With steady-state DC there's no inductive or capacitive reactance to provide reactive power as there is with AC so the only load you see is resistive, even if there's an inductor or capacitor in the circuit. But when you turn the circuit on or off, you're generating an AC component (step function), in which case you will definitely see the effect of the inductance and/or capacitance.
Likewise a dc motor running with a steady load will look resistive to a steady-state DC supply (although it may add some hash noise to the line from the inductive switching through the brushes). Again the motor inductance effects will show up primarily during turning the voltage on or off.