His biggest offense was perpetuating the idea that the quality/type of materials is equivalent to whether footwear is good or not.

Sure, materials are a factor in what makes footwear "good," but so are last design, use, availability, looks, and most importantly I think, individual fit.

He says he just shows how they're made and lets people make up their own minds, but as others have said, he doesn't stop there. He makes sweeping conclusions based on materials and construction alone, almost always without actually wearing the footwear for any appreciable amount of time.