In the hereditary world, it takes zero mental capacity to be a world leader. Dead people have even pulled it off. In the democratic world, being smart almost certainly bars you from office as the average person is put off by smart people. Democracies naturally promote the worst, not the best.
I don't really agree with that. I think that, for office, you have to have some smarts. It's problematic to come off as intellectual, yes, that is certainly true. But actual stupidity doesn't pay. I think it pays to be good at looking stupid while playing 'the game' very well.
Not saying that office attracts the SMARTEST people, though, nor the kindest or best. And about the puppets, Frank Herbert said: Power does not corrupt, but power attracts the corruptible. If he is right, we should elect people for office who aren't interested