I agree with the idea that its mainly a team effort. Unlike Carmack & id Software, when I look at the people such as Factor 5, Crytek, Nintendo, Guerrilla, Naughty Dog, Square-Enix etc. its really tough to say there is one distinct person that drove the technical marvels and ground breaking tech seen over the years from these companies. In many cases, its also the directors and artists that push for certain things to be realized.