The reason you find it 'retarded' is simply because you're not assessing the importance of a slogan in a business perspective.
A) teachers aren't selling anything
B) sales-pitches are used in jingles that stick to the human psyche and repeat themselves (if catchy) which is ultimately the whole point of the marketing to people who are exposed constantly to the catchy sales-pitch.
C) Restrictions are not all that 'simple', the restriction doesn't apply to people who simply utter it for any other reason that doesn't include selling a product.
It might seem frivolous, but both, jingles and slogans, are important to company sales since the jingle or the slogan conjures up images of that particular company, and that's where the companies aim at. Use the old noggin guys.