I'm not sure this is entirely related to your point, but I've recently been thinking that intelligence can be detrimental to promotion, in that intelligence pro

I'm not sure this is entirely related to your point, but I've recently been thinking that intelligence can be detrimental to promotion, in that intelligence produces questions and disagreements and non-conformity, which are all traits that make the job of Management more difficult. Making life difficult for Management is unquestionably NOT a path towards promotion, and continues the rotating door of mediocre management. And mediocre management wants, desperately, to hold on to their position because they're aware, consciously or otherwise, of their mediocrity. Having someone who can out-think you as a report is a threat to your position. Like you said: fear.