I agree with most of what you are saying, but it's not really what most people look for in a "ranking". If you rate undergraduate institutions based on the actual program, you would see schools like Miami U in OH, and William in Mary in VA at the top of the list. HYPMS might not even make the top 10. However, people will kill to get into these 5 schools because they are known to be the most competitive, produce the most job offers, and give you a reputation which gives you an advantage for the rest of your life. Simply put, nobody turns down HYPMS to go to Miami U, even if the program is better.
Similarly, in MBA rankings, people want the most competitive class, the best "seal of approval" on their resume, and the highest ROI on their money AND time. When you consider this, any ranking which doesn't have H/S/W at the top probably doesn't reflect what people are interested in. Furthermore, if you look at applicant profiles from H/S (and even Wharton as well), they are notably different from profiles of other top 10 schools. GMAT doesn't even tell the whole story as these schools are known to reject 800s.