Well, CEOs may be inherited from non-optimal initial conditions of early ancestors and simply haven't been replaced by a better competitor yet. Or they have been and we don't understand that yet. Naturally occurring genomes encode for processes that result in all sorts of things that don't actually have to occur. The appendix, the frenulum, most of the DNA itself, as far as we can tell. Nature's full of random dead-ends that keep propagating because the system hasn't gotten over the barrier of the next local minimum yet.