People don't have nearly that tight of control over the workings of the world. It would really be far more beneficial to have more people engaged in affairs, as the challenges faced by managing an ever expanding population outpace the abilities of individuals to direct events. The problem is that many people are hung up on personal fears, and end up using whatever little powers they might obtain to lash out at whatever spooks them.
So yes, efforts are made to ensure that actors with influence are actually fit for their roles, and to keep those who are unfit busy with anything else.
Regardless of what reasons you ascribe to events, however, it's still true that fear is a major force which prevents large segments of the population from focusing on whatever is most pertinent for their own advancement through life.