The CEO saw a problem and clearly communicated it -- you've gotten results but cannot explain how or why, and that isn't good enough going forward
That is clearly the CEO's point of view in this case, but it's a view I find rather perplexing. It leaves no room for intuition and good judgement. Potentially, it can force people to try and write down explanations of stuff they are not actually confident about, which just end up confusing whoever comes next.