cream of the crop = ?
stellar undergrad? stellar work exp? great potential? fantastic out-of-work achievemens? healthy mix of above without too much of each? Kind of hard to state that by looking at a few anecdotal examples.
No single degree stream has only 'cream of crop', but I would hazard a guess that top MBA institutes do have a high percentage of achievers. Again, why someone wants to do an MBA could be based on myriad reasons and we all know what they are. In many organizations, your fast track career comes to a slow motion painful stop once you reach the borders of top management. Suddenly, you are competing with 10 others whose work experience is probably as good as yours, but oops - you are relatively 'under qualified' and it *does* make a difference. By then, it's also too late to 'go to school'.
If we're talking about those 'super exceptional superstars' defined by making millions by the time they are 30, have 10 promotions, lead their own multi million $ companies - they are statistically insignifcant in number and I would humbly say i'm not one of them and I need an MBA ;)