I've approved this message

What is the deal with the political ads? When I heard Lyndon LaRouche putting his radio ads on the air I thought he was nuts because he begain every ad by saying "This is Lyndon LaRouche, I've approved the following message". Now it seems like every ad I hear has the candidate saying "I've approved this message". If I see the candidate talking to the camera during the ad the I pretty much figured out that they approved the message. Why do they need to use these magic words? Maybe it's just me but it gets old after a while.