Your service adviser is absolutely correct and better educated than most. Most modern cars and light trucks use what is called a single or non-servo rear brake. These brake designs have the self adjuster connected to the parking brake assemblies and do require park brake usage to ensure rear brake adjustment. This not only ensures proper rear brake operation but also helps keep the brake pedal high and the brakes functioning better keeping excess load from prematurely wearing the front brakes. The days of having to sharply apply the brakes while moving in reverse are almost gone; some vehicles still require this, so check with your brake system specialist to find out what kind you have.