Ask most people what the key line is from Field of Dreams, and nearly everyone will say:

If you build it, they will come.

On a near regular basis, I talk with people who subscribe to this methodology.  If you build a great product, if you send out the mass emails, if you do all these things – well then customers will magically appear and money will start to flow.  There are quite a few stories these days about how salespeople will become irrelevant because people will just magically find web-sites and buy stuff.