Just because advertising has infected other mediums, doesn't mean that advertisers are entitled to infect everything.
Leela: Didn't you have ads in the 21st century?
Fry: Well sure, but not in our dreams. Only on TV and radio, and in magazines, and movies, and at ball games... and on buses and milk cartons and t-shirts, and bananas and written on the sky. But not in dreams, no siree.