I personally think there are more CS graduates that start businesses than MBAs. From what I have seen, most MBAs become consultants or executives of existing companies. I could be completely wrong here though as I am speaking based on people I have met and not actual statistics.
I think the point that's trying to be made here is that you don't need an MBA to make it in business, which I think is a very valid point. You just need the entrepreneurial spirit and drive, along with the technical expertise (if you're in software), not the MBA.
About 10% of Oxford's Said Business School graduates start businesses, I'm guessing that's quite a bit higher than most CS degrees.
LBS run an entrepreneurship summer school which concentrates on the entrepreneurship parts of their MBA program. Over the last 9 years they've had 350 graduates, and produced 90 businesses. Of those 90, 80 are still operational, which is a fairly good success rate.
Although I completely agree with you that you don't need an MBA to be successful in business, much like you don't need a CS degree to be a good developer. But if you're weak in those areas that the degree covers then obviously there will be value in studying those areas.
I think the point that's trying to be made here is that you don't need an MBA to make it in business, which I think is a very valid point. You just need the entrepreneurial spirit and drive, along with the technical expertise (if you're in software), not the MBA.