Because that's not how organizations work. Especially not organizations made up of MSc's and PhD's, each with specialized knowledge that the CEO has no clue about. It's a myth that the person with the most power is also the most important.

Instead of asking for elaboration ask yourself why you believe that the success of companies hinges on the qualifications of their CEOs? To the best of my knowledge no one has ever shown any correlation between CEO "quality" and company performance for a publicly traded company.