They sell products, shape public opinion, and entertain.
But what about those disclaimers?  The tiny print at the bottom of the TV screen that can  only be read by a speed-reader with binoculars.  Or that totally inaudible whispered part of a radio commercial.  Let's not kid, disclaimers aren't especially good for sharing information.  So why are they used?  Because by law, advertisers are required to tell you certain details.