When every fodder scabbards injured him, but none of them can give him a lasting scar.
Where it get debunked, it said that he fought 18times against the Navy and other Yonkous and even get caught up, your point would speak against the fact with we get from the manga information.
Yonko term appeared after Roger's death.
BM didn't see him in decades, he didn't fight against her.
WB didn't want to fight against him, and his words implies that he would get his revenge for Oden (killing him) but with many casualties.
The only one against he probably fought some rounds is Shanks, and it doesn't seem to be a long battle, a battle to death, etc.
So all that info was debunked, false hype.
Kid and Killer fought in previous battle with Kaido too, they where surprise that Luffy could hurt Kaido.
Kaido totally debunk any point of your with saying blades usually not hurt/give him a cut, when he get cut he directly say about ryu.
With means usually blades without ryu couldn´t hurt him in the past. So what is your point, your headcanon vs Kaido own state?
Killer is surprised because Luffy DAMAGED Kaido.
Damaging =/= hurting
I fucking explained already with the mosquito example, holy shit how didn't you get it. A simple mosquito can make you bleed (can hurt you because, it can pierce your skin) but the DAMAGE is INSIGNIFICANT. A kid fist would make more DAMAGE than that but it won't make you bleed.
If we assume that we have a health bar like Tekken/DB/etc characters in games, in the first example you won't be able to see with your eyes how the bar health decrease since the damage is trivial while you will be able to see how the bar decreases in the second example.
Killer and Zoro's attacks, as well as scabbards attack could hurt Kaido, could pierce his skin and make him bleed, but his bar health barely changed (mosquito bites) while Luffy's punch make his bar health decrease significantly in comparison with the others.
The first step yes, the second would be something like gammaknife with is simple a hax ability, destroying anything within, so your point is again totally false so move on.
Neither of them are hax. The internal attack still need to "clash" with the target's organs' durability, is not "zero". If the external defence has 100 points, the internal defence (organs, veins, etc) still have some points of defence, 15 let's say, or even more.
Yet the only few character who actually hurt Kaido where always people who could use Ryu, with means your point doesn´t make again nosense since their wasn´t any enemy who could hurt without a strong Ryu.
Explained already.