And that was exactly the point I was making here. You are having an utopian ideal of what a Yonkou should be and because BM doesn't fit that ideal, you don't like her, but your ideal doesn't conform with the reality. The Yonkou are pirates or with other words criminals who don't follow laws or rules other than their own. They murder and steal whatever they want whenever they want and they don't listen to anyone other than themselves.
You are trying to make the Yonkou appear like some misunderstood anti-heroes, but they are essentially twisted figures. You say that Garp has a serious side that balances things out, but do you think that BM is not serious? As she is bloody serious. You might think that all of these tea parties and whatever are childish, but to her it's the norm. She transformed her fantasies into a factual, dreadful reality and everyone has to conform with that reality or they die. That's what makes her a Yonkou and you don't seem to understand that. What you describe would be suitable for an admiral, but not a Yonkou.
And frankly we have a world leader that pretty much fits the description you gave, namely Donald Trump. Putting that aside real life examples are by default misplaced here as even Trump and Putin are dependent on other people. That's not the case for BM as she can do whatever she want and try to laugh at her for doing so. Power, shear power taken the form of a single existence. That's what Yonkou are and looking at real life is plainly wrong as there has never been a person who resembled a Yonkou. Frankly the entities that are most closely related to them in real life, are gods, demons and titans which don't have to be smart, sensible or sharp as they will be revered and adored both out of fear and awe of their power.
The truth is here that it's Shanks that's the odd one out, not Kaidou or BM and the admirals and the Gorosei are two completely different entities. Your problem is that you don't seem to apprehend what a Yonkou actually is. They are different from real life, different from the admirals and different from the Gorosei.