With power in city downtowns (eg San Jose) at $0.50+/kWh it’s definitely becoming a huge factor. My Mac uses almost an order of magnitude less power than the PC and I keep the PC powered off.
Either you are not measuring power consumption correctly, or there is something very wrong with your PC.
And it's an entirely believable statement. A Mac Mini uses between 5w - 20w. Many PCs idle at >50W, and under use hit 500W+.