Thanks - good post. That said, I don't think Fred Wilson was being unreasonable.
I'm far from an expert but I'd agree that the ad business is a tough one in which to succeed, maybe not when contrasted w/ mobile apps or gaming, but certainly when compared to other web businesses with more distinct revenue streams like enterprise solutions, etc.
Perhaps the founder of a successful advertising-based business such Bleacher Report would disagree, but he has good reason to do so!