Warcury has shown creater durability than Kaido indeed. But we know that's only one of Kaido's stats. He also has incredible endurance and offensive stats, including high level CoC. Luffy has yet to smack Warcury (or any other elder) with ACoC amped attacks. of which Kaido took a shit load. Like no selling an ACoC KKG with his Boro Breath exploding in his mouth while already heavily fatigued.