Maybe not even then. I don't have the reference in front of me, but I seem to recall something about a study of the Fortune 500 CEOs, and there were as many from some state school (University of Wisconsin, maybe?) as there were from Harvard.
Edit: some links about this point.
http://content.spencerstuart.com/sswebsite/pdf/lib/2005_CEO_... (Warning:PDF)
http://bernardmoon.blogspot.com/2009/05/go-wisconsin-most-fo...
http://www.usnews.com/education/best-colleges/articles/2011/...
Here's another fun observation from that 2005 study (said as a North Carolinian who resides in Chapel Hill):
Of the Fortune 100 CEOs, the top schools for their undergraduate degrees were:
Harvard, Stanford, Yale, U. of North Carolina - 3% each
Which one of these is not like the others? :-) (To be fair though, even though it's a state school, UNC is generally pretty highly regarded and their business school is usually pretty high in the national rankings.)
MBA isn't for leaders - it's for followers, just very well paid followers.
Otherwise the world is full of middle managers who were sent on low grade MBAs by mega corps who didn't know what to do with them and couldn't fire them
When you are interviewing managers were given a year off by a now-defunct multinational to do an MBA, ask how all the projects they claimed to be deeply involved with managed to run without them during that time.