Points well taken as far as they go. A more basic explanation: All (MBAs or non-MBAs) can't be CEOs, simply due to pyramidical organisation structures. There is thus less room at the top, and some must go.
About MBAs vs. non-MBAs: a) Many of the examples are of entrepreneurs who have successfully made the transition to CEOs, and are thus non-comparable. b) As a % of corporate entrants, MBAs do better than non-MBAs - perhaps due to of a faster learning curve plus self-selecting admissions process. c) Irrespective of background, competencies needed for the purpose have to be built. d) MBA is just one way of getting a management education. e) Such education has to be on a continuing basis - this seems to be deficient in India. f) This is the way forward in increasing the proportion of effective CEOs, irrespective of original educational background.
In sum, we need more empirical research to help: - make definitive statements in the matter - design interventions to tackle underlying issues.