The author's point is that "We like to pretend that academic scores/grades are instructional and Pedagogical, but really they are motivational/game elements. The reason to work hard is to get a good score." Also, "We also like to pretend that scores are scientific, when instead they represent a staggering editorializing of what is important, and by how much." This is why quantifying my blog's success is ridiculous. It's not that you can't count anything about my blog. You can. But in so doing, you misrepresent the reason why I am creating the blog and misrepresenting what's important about it. The same for business blogs. If you are quantifying the blog's ROI, I content you have misunderstood the point of the blog and its value to your business - your desire to measure its effectiveness will ensure that you minimize it.