Phong and the Rendering Equation: What's with the cosine?
The cosine term in the rendering equation is to account the amount of light reaching the surface, and leaving it out from the rendering equation is what he refers as "complete nonsense", which is right. The original Phong model didn't have the cosine term in the rendering equation, so if you want to model the original nonsensical Phong with proper rendering equation, you need to hack it by adding the cosine denominator to the Phong BRDF.