Luffy’s fight against Katakuri proved that even with the introduction of Haki Oda still retains the ability to make interesting and creative fights and it’s not all about who has the stronger Haki.
Luffy beat Katakuri, someone who had the clear advantage on him in everything but endurance.
- The “superior” Devil Fruit;
- Way more advanced Observation Haki, with Luffy barely even attaining the same level of it near the end of their fight, a level Katakuri has clear mastery over;
- Superior Armament Haki with his Block Mochi reinforcement, to a level where a mere clash of fists hurt Luffy but not Katakuri;
- An Awakened Devil Fruit;
Compare that to the only thing Luffy did better than Katakuri:
- He’s used to getting beat up a lot;
Katakuri barely, if ever, took hits anymore after attaining his mastery of Observation Haki while Luffy gets beaten around to the point of being unable to move after a fight every other arc. That (and his will, I guess) is the only reason he could even fight with Katakuri for such a long time, not even being able to touch his opponent for the majority of it while taking many hits himself.
If Luffy’s fighting style was focused more on dodging than it already does he probably wouldn’t have won this fight, especially not after the point where they stopped doging each others hits after the Conqueror’s Haki clash.
Katakuri asked himself “How many years has it been since I’ve taken a hit?” after Luffy finally managed to land one (and that only because Katakuri himself lost focus of his Observation Haki), indicating that his endurance, while impressive, might not be the best. After all, why bother with defense if your entire fighting style revolves around not getting hit anyway?
*Theory by LeavPrime