Whether we're "taught" that or not, it is certainly not true and comes across as an elitist attitude. There exists plenty of awesome, original content that no one will ever hear about because it's on a website somewhere with no way to really find it without going to page 10 of some specific Google search. Marketing and advertising has its place, and I'm thankful for advertisements sometimes when they have lead me to finding a new product or service that I enjoy.
If you are really taught that, then your teacher has done you a great disservice.
The most original product person in tech's history was also one of it's most brilliant marketing and sales people.