Almost none of the trading heads had an MBA. Even within the traditional management, few of the ex-consultants had one. And yet the business is one of the oldest ones in the world. The key is that the main requirement for moving up was the value created for the firm (which was and still is privately held, mostly between the founding family and the head traders); this did not seem to correlate with having an MBA, but the firm culture was to grow talent rather than hire outsiders.

I've seen businesses where MBAs hire more of themselves "at competitive salaries" and nobody actually has any hard skills. Those have very negative cash flow, but also are very good at raising more money to match it. Not a fan of the degree, but maybe I just saw the bottom of the barrel.