If you've ever been stuck in a drive through for a while so it gets hot, then you re-enter traffic, your fan will be locked up and you'll sound like a school bus/ dump truck. Also you'll feel it grabbing horsepower.
Next time you've driven your car "normally", go out there after you shut it down and spin your fan by hand, it will (should) barely have any friction with its hub, in other words, basically freewheel.
The other accessories... alt and power steering, are just along for the ride. If your belt is slipping or whatever then the total load of the accessories will cause trouble at high load.