I agree with you, these qualities are not intrinsic to leadership. But subconsciously (or perhaps consciously), others see someone who is healthy, vibrant, and

I agree with you, these qualities are not intrinsic to leadership. But subconsciously (or perhaps consciously), others see someone who is healthy, vibrant, and well-groomed and, knowing nothing else about the person, they will infer that this person is in control of their dietary habits, fitness, and hygiene. It's easier for someone with the appearance of health to convince others that they are a leader than someone who appears sickly or behaves slovenly. Again though, like you said, it's not intrinsic. No one would argue that Churchill was not an excellent leader, even if they did disagree with his politics or his methods.