@ Rob, this is easily said, but I am yet to see anyone that has actually done that. I mean - sell a vision w/o crafting a single line of code.
And there is reason why it is NOT possible. We live in times when the idea that an idea can become something big, is really big. And this idea is being pushed through every single channel you can think of - movies, social, tv, books, even companies' stories are built around the idea, that it was 'the founder's big idea' that mattered. Because it is sexy. As a result, we see huge spike in startups.
Now, if you have a huge supply of startups, you will see big competition for resources. Resources include developers, investors, salespeople, and everything else involved in the 'startup economy'.
When you have huge competition like that, whatever you are offering needs to be better than the next guy, or you stand no chance. This is the key. That is why you have to build your product. MVP is the compromise to build something useful to test your hypothesis vs building the real product. The MVP should be good to compete for investors' money and to do that you need traction. To have traction you need sales. No salesperson will go around with bunch of printouts with your vision and actually be able to sell it. People are smarter that that and it has been like that for some time now.
Of course, you may find a genius, amazing sales person who can sell, before you need to build the product. And his story will be propagated all over the Internet, movies, books, everywhere. Some people will believe, but they will forget the facts that this genius was also well connected, had previous companies and probably the economics to spend the time to go around and sell w/o pay for a long time.
Sure, I might be wrong, but this is what most of the entrepreneurs experience (at least the ones I have met). In our current market situation, having a product to sell is the only way I see it for a startup to progress. In my opinion @Ema's view is much closer to the reality.