Kaido is a unique case, its not like he just has high endurance he is actualy unable to get hurt at all unless you have some specific kind of haki, like internal destruction and warever the scabbards where using to bypass his skin.
Soo you are correct, Kin'emon couldnt do shit to the Pica statue that was about to squat him and everyone else in the plataform, yet he has knowledge of a technique Zoro dosent have, that dosent mean he is a stronger fighter than Zoro, or even Sanji who has barely shown any no CoA at all.