I say that it's stupid because that's what I heard when I asked someone about it, in real life that is. Now that I know you are very sensitive, I won't say anything like that again.
My father towed his race car the day that he bought his new truck, which he was advised not to by the dealership. With 39,000 miles on it, the truck hasn't skipped a beat, gets more than the EPA mileage, and goes like a sonuvabitch.
About the breaking in thing, I was told by an engine builder there isn't a set break in period. Usually with racing motors we build, we set it in the car, let it idle, set the timing, then rev it to about 8,000rpm(usually dealing with SBC and BBC's) three times and if it doesn't blow, you are all set. Usually anything bad that is going to happens, happens within several minutes after first firing the motor, cam going flat, bent valves, etc, etc. I realize that street motors are different from racing motors, but they work on the same principles.