You missed the point I was making. That was, just because two characters can clash evenly it doesn't mean they are equal nor doesn't mean the power that they both possess is equal. There are logical explanations for that. The amount of power used or other ability and power could be the reason.
Luffy didn't only fight Kaido in base mode after he obtained ACoC. Luffy fought Kaido in all his modes except for tankman and he still lost. That was after he lost in base mode the first time, was rescued and given food for energy. Luffy only won because of G5 (awakening) that came out of nowhere. Even with G5, Kaido was dominating the fight the majority of the time. As I stated earlier, nobody in One Piece is strong simply because they have haki and only haki. Everybody has some other power, fighting skill, or ability they use along with haki.
You are the one making everything convoluted. There are 2 important things the manga tells us about CoC.
1 - Characters cannot increase the strength of their CoC by training their CoC. It can only grow stronger by the user growing stronger.
Characters can only train CoC to become better at controlling it.
That means you cannot determine the strength of a character's CoC by how strong they are with their CoC. You have to look at their strength without CoC. The stronger a character is, excluding CoC haki, the stronger their CoC haki is.
That explains why Luffy went from getting his ass kicked to going toe to toe against Kaido just by obtaining ACoC.
2 - The skill to flow and coat thing with CoC is the same skills used to flow and control CoA. It's just applied to CoC, instead of CoA.
That doesn't mean everyone can learn ACoC. But that does explain to us why Luffy and Zoro both obtained ACoC and became skilled at using it quickly.
As you can see, the fact Luffy has more experience with CoC and better at knocking out opponents with it doesn't mean his CoC is stronger or he's more skilled at using ACoC than Zoro.
It's hard for some people to accept that because based on Zoro's rooftop performance and strength Zoro's CoC haki strength is similar to Luffy's.