it may not be good for your paintwork , i would agree especially if you wash your car every weekend in a carwash....but with good polishes and hardness of paint...once a month in carwash shouldnt be a problem.
Dont forget when you sell the car, the dealer doesnt give a toss about howmany times you polished a car or washed i t in a carwash...i do think black cars in car washes is the worst thing ever for swirl marks