Yeah via ryu soo your point?
Ryuo is not special, like I already proved with the expalantion of Hyogoro, is gathering more Haki in the same place, that's why is above normal Hardening, so, it's more AP.
Whitebeard didn´t invade Wano, fighting Kaido outside of Wano make more sense since Kaido challenged them most like without his crew, so your nothing you said is a point, in the fact that the state her in picture is from the narrative speaker, with meaning>Oda saying these stuff and not a random character in one piece verse.
Same goes for Shanks who is a Yonkou since 6years ago, soo he could fight Kaido multiple times too, their is no any point who speak against it or do you have a fact/manga panel as proof? I doubt it...
No, WB and Kaido never met in the 20 years after Oden's death, that was implied with the explanation we have so far. Maybe they never met even since God Valley incident.
And this wasn't implied by a random character, it was by Marco, Izo and WB words in that mini flashback.
So the narrator introduction is fake hype.
Like I said, Shanks is the only one who maybe fought against him since there is nothing proving the opposite, so for the moment we can assume that. But that doesn't matter for what I'm saying about the fake hype, since the narrator there implied that Kaido challenged ALL Yonko, which is false like manga proved in these chapters in Wano.
And again Killer didn´t really damage Kaido, he couldn´t give him any cut/wound, same goes for Zoro, both didn´t use haki/(or ryu in case of Zoro) yet, the Scabbard use Ryu to damage Kaido so your point doesn´t again make anysense.
Ofc he/they didn't damage him, they could hurt/wound his skin, but nothing relevant in terms of damage. There is blood drawn in that panel.
So how it does not prove my point? They cut his skin but it was like a mosquito bite, irrelevant damage.
It depends who get hit by the hax internal attack, someone as Kaido can tank it better then any high tier character, as any other hax ability it depends of whoo get hit, with means internal CoA is still a hax ability or would you say Gamma knife isn´t a hax ability too??
Sanji had some of his organs pretty heavily damaged against Kuroobi, so it's not impressive to tank or endure that kind of damage for physical powerhouses.
They are not made of crystal inside, so it's far for being hax.