The Power of Free | For Entrepreneurs

Another way of looking at this kind of business model is that you are using engineering resources to solve the problem of how to acquire customers.

Conventional thinking places the burden of acquiring customers on the people in marketing and sales. A free strategy requires a different way of thinking that usually has to come from a founder or CEO. In the Free strategy, the company is going to shift the expense of customer acquisition to the product development group.
(Link: The Power of Free | For Entrepreneurs)