Advertising can also be helpful -- it is possible to develop a new product which is useful while not being intrinsically viral. Advertising makes it possible to have such a product actually exist and benefit people.<p>But impression or persuasion based advertising is generally unhelpful or actively harmful.<p>I recently ran across a fascinating (and scarily dystopian) take on the future of that sort of advertising: <a href="http:&#x2F;&#x2F;escapepod.org&#x2F;2013&#x2F;05&#x2F;16&#x2F;ep396-dead-merchandise&#x2F;" rel="nofollow">http:&#x2F;&#x2F;escapepod.org&#x2F;2013&#x2F;05&#x2F;16&#x2F;ep396-dead-merchandise&#x2F;</a>