"If you're going to be CEO, either of a startup or a large co, you're probably broadly competent or hyper-competent in a handful of areas." Any particular reas

"If you're going to be CEO, either of a startup or a large co, you're probably broadly competent or hyper-competent in a handful of areas." Any particular reasoning behind this? Why would this particular specialty (abstract people management and capital allocation) be more likely to attract competent people than any other job specialty?