I read this same thing more than once last year when doing some brake rotor research. Specifically, they were talking about bedding in new pads and the heat induced into the rotors while doing so. They were adamant about NOT sopping the car and holding the pedal down for this same reason... I've forgotten the details, but pad material transfer was mentioned, and that the pads act as a heat sink against the rotors when stopped could cause issues. Therefore I often shift into neutral (Florida roads are typically level) at lights....It seems like I read somewhere once that hammering the brakes for a quick stop and then leaving the pads clamped onto the rotors at the stopping point will do something to the rotors... so that their surfaces are no longer true.