His examples don't really fit that though. For small ranged lights (lightsaber) or lights that are relatively short lived and intense (explosions), you can totally get away with not casting shadows. Also I don't see how threads would really help with rendering more shadows, other than providing a generalized speedup. The cost of the shadow map is really more in the GPU shaders than any sort of CPU calculation.
For stencil shaders threads might help, since the CPU has to calculate and upload them frequently (unless you're doing stencils in a geometry shader). Stencil shadows are pretty niche though, you only use them when you need pixel-perfect precision. Shadow maps are vastly more popular.
And yet none of what he talks about does anything to help that. I'm not against oversimplifying, but what he's saying is entirely bogus, shadows being expensive has nothing to do with how many threads the CPU can issue commands with.
He's setting up this notion that the problem with graphics is a lack of threading, which is ridiculous. Graphics code is incredibly parallel, and his assertion that graphics work spends most of it's time constrained by waiting for the CPU just does not add up to me. Except in poorly written systems, I just haven't seen this be the case often at all.
