Slightly different principle as the axle itself is rotating, and the nut is just retaining the wheel. Imagine your bearings are wearing in your wheel, and there is now a loading trying to turn the inner race along with the outer race. That in turn is loading the spindle and trying to turn it along with the wheel.
I agree the forces on a properly maintained machine are minimal, I just prefer to follow engineering practice. (The company I work for makes high speed packing machinery so we deal with a lot of bearings, shafts and similar parts).
I guess they factor in the possibility that the axle might sieze to the wheel if it's not lubed.
Just that, Studley....