Yes nice analogy.....
The thing is you could push the car back on to the road.The power is needed to get past ,or blend back into traffic.It's not need to get the car back on the road per say.
Now if your room is covered with absorption...you need more power...because you have traffic
Your amp is massive ,hard to get you simple SIGNAL through.....because you have traffic.
Your speakers weight tons ,you need power to get the delicate SIGNAL through.....because you have traffic
your wires are 1 inch thick.delicate SIGNAL needs power to get through .....you got traffic.
your stuck in this massive traffic jam ...your delicate signal is.....you need power to push it through....BAD FOR MUSIC IN THE END