Because Luffy said literally "it's hurt right kaido ?" so that means kaido would have been hurt. not hard to understand no ?
I know lol
Same for Hiryu Kaen, the only difference Hiryu Kaen with the parallel with Ryuma and Zoro being healthy, it won't just hurt but also kill
Here is the problem you use a theory to justify an other hypothesis. It will be acceptable if ZKK was a fact and not a theory.
As for the parralel with Ryuma we don't know how tough was the dragon he beat.
So nothing states the same attack will Kill Kaido.
Especially when an attack like Ashura failed.
Zoro cut the horn like a butter, so
It's just some background nothing comparable to an actual Character. Basic Shonen logic here.
i don't remember Big Mom screaming and asking Kaido to dodge for others attacks ?
I don't remember Kaido dodging an attack by himself.
and if Kaido didn't dodge then it's worse because that means he is still fine because of Zoro's miss.
You don't know what will happenned if he didn't dodge it's just your assumption.
I'm just using your own logic nothing more.
As for why Oda did that it could be because he want Ashura with CoC being Zoro best moment on the Rooftop. After all it's this moment who was the most enlightened in his VivreCard.
The same Ashura who was the one to be coated in CoC