Unfortunately, there's a lot more to that first milestone than sitting down to hash out some code. In just about any size business, a project will require the programmer to work with a multitude of other professionals around the company. Imagine you're one of those people and for every project you have to deal with two or more people not only for the initial briefings, but for ongoing support where they're likely to ask similar follow-up questions and require at least some maintenance. It's not so simple that you brief and follow-up with the programmers simultaneously either; doing so would misrepresent their skill sets and unfairly level the playing field, thus mitigating the initial intent to discover the best and brightest at that particular project.
I imagine the cost in this paradigm actually exceeds the simple salary of the extra programmers, but also includes the time, energy and frustration of the other employees who must deal with the redundancy.