Don't take this the wrong way, but I feel like you are undervaluing short fat engineers. :)
The article isn't saying that specialists aren't valuable. In fact is says the opposite: "If you know exactly what you need, and you need it right now, choose depth." It is just saying that perhaps the short fat engineer would be the one who realizes they need an OpenGL specialist on the team in the first place because the graphics are hitting a bottleneck and slowing down everything else. The author is merely pointing out that in the nascent portion of projects their contributions are, at times, under valued.
The article isn't saying that specialists aren't valuable. In fact is says the opposite: "If you know exactly what you need, and you need it right now, choose depth." It is just saying that perhaps the short fat engineer would be the one who realizes they need an OpenGL specialist on the team in the first place because the graphics are hitting a bottleneck and slowing down everything else. The author is merely pointing out that in the nascent portion of projects their contributions are, at times, under valued.