Oh, I comprehended that post well, it only said roger was a pirate king because of his crew and I also said you are wrong. Roger started the whole Journey by using his charismatic and caring personality to recruit people to his crew,
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And I am pretty sure he recruited all his other members the same way as luffy has done. If left to their own accord Rayleigh would never have become this stronger. And the entire crew became strong because they wanted to help their captain and that is the power of a CAPTAIN. But when you even impress someone outside your crew that is the power of a KING.
It was entirely because of Roger alone that he got a crew a new ship and actually reached raftel because roger.
And the point that you seem to conviniently ignore is that I drew a parrallel of roger with luffy that the captain always takes care of the biggest bully in the playground. Which means Roger also fought the strongest himself throughout his journey to be the pirate king. All roger's crew did was take care of the other fodders, so while we can give them credit to have helped roger become the pirate king [Since it is clear as day that one man cannot fight a pirate crew like the Whitebeard's all by himself - he will only battle whitebeard or garp not Aokiji (his underling at that time)] it would be extremely ignorant of you to think that Roger only became the King with that crew. He would still have recruited other people and still become king.
That being said, a Pirate King still needs to defeat all his opponents and establish his dominance among all the other captains to be accepted as the king. So Naturally becoming a pirate King mean you have to be strong, strong enough to beat both garp (can be considered even above admiral level) and Whitebeard.
Coming back to Luffy's achievements on impel down and marineford? Breaking out of the most secure prison in the world all by himself in itself is a big achievement, and then bringing Ace right upto the rescue ship is also an achievement. And if you think that all these achievements are not due to luffy, think again.
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Highlight on what Mihawk thinks.
My Earlier post was actually pretty clear, but I guess I needed to be more elaborate in your case.
And If I need to dumb it down further, just understand that only one man is called Pirate King and the other members on the crew are simply members of his court with Rayleigh being the defence minister.