Zoro cutting Kaido is not a reliable feat, it's the only attack he really did, he was disappointed by it and compared it to Luffy's attack, "I couldn't knock you down", Luffy did, so Luffy's Red Roc > Zoro cutting Kaido
And it is not a reliable feat, because it is just one attack done in a 3v1 against a Kaido who was holding back very very much, later in the Luffy fight it is said his haki gets stronger, he stops holding back as much, and because if you look at Luffy's red roc only, you would say "Oh man Kaido can't even stand up to Luffy, Luffy would just constantly knock him down"
Zoro cutting Kaido is as irelevant as Luffy knocking Kaido down with red roc, it is not reliable and only happened in a fight with Kaido holding back a lot, with many other people to help, and looking at it alone and not at all the other things around it is the only way it seems impressive
And Oden hype is not, he cut Kaido, Oden hype is he did one attack on Kaido, and it was implied that if the second attack landed Kaido would have been defeated, two shotting an emperor is the hype
And King's durability is nowhere near Kaido's, I think it is very disingenous to claim that this random YC1, who has an invincible mode, was talking about his actual HP when he said his durability is on another level, instead of about his actual invincible mode