I think most companies don't realize that businesses are always about people; they are composed of people, run by people, and sell their products/services to people. When it comes to the composition of a company, having camaraderie and talent goes hand in hand. The moment you hire someone who is average or doesn't fit, the entire work force degrades gradually.
Thomas C. Shelling developed a statistical model that actually describes this behavior and shows how a class of people clump together (http://www2.econ.iastate.edu/tesfatsi/demos/schelling/schell...). This is why talent attracts talent and mediocrity attracts mediocrity.