OnePiece| Why Gol D.Roger Had No Devil Fruit

Gol D.Roger "The Pirate King" is said and is also believed to be one of the most powerful pirate in OnePiece. I Personally believe that Roger did not have any Devil Fruit Power. One of the biggest proof of him not having devil fruit is that he was not wearing any Sea Stone Handcuffs when he was getting executed in Louge Town. He was already known as the Pirate King and even World Government wanted him dead so why would World Government think of not putting a Sea Stone Handcuff on one of the most dangerous pirates in the world when he was getting executed. The Proof Roger was wearing a wooden handcuff is shown in the picture below.

I believe that just like Silvers Rayleigh even Gol D.Roger was master of Haki and he was the person who created Conquerors Haki (Haoshoku Haki).The name Conquerors Haki was given as it was used by the person who conquered GrandLine and became the Pirate King. It has also been disclosed that conquerors Haki is very dangerous and only limited people are able to use it. Just like many people and theory, I also believe Haki is Will Power and People having "D." in the middle name have the most powerful will and hence is referred to as the "Will of D.". So there might be a difference in other people using Conquerors Haki Like Don Chinjao and people who have "D." as their middle name. Even though Rayleigh has no devil fruit he was able to hold Kizaru at his old age. Kizaru even said that he would need more dedication than what he had when he was trying to catch Strawhat Pirates simply stating that Rayleigh was very tough to beat even at that age. If Rayleigh could easily hold off Admiral just using Haki then Gol D.Roger Could as well and on the top, he was said to have a strong will. Gol D.Roger was also paired with Garp and also considered each other as a rival in OnePiece. Garp who was a Marine Vice Admiral(Not After 2 years TimeSkip) did not have a devil fruit as well. Hence, I think that Gol D.Roger did not have a Devil Fruit Power as well.