This is simply copium. Or you arent taking seriously Kaido's words.
Your examples work on fodder but you haven't seen the peak of haki yet.
According to your argument, Zoro doesn't need stronger haki than Mihawk because he can beat him with Asura.
Funny enough, this was my own argument when I was saying that Zoro is already the strongest in the world.
I have realized that it is just copium and nothing else. Mihawk cannot be beaten through sheer force.
As long as you don't surpass his haki, he is unbeatable. That way Zoro's dream is also impossible for all others.
Completely wrong, Zoro is the only one who can surpass Mihawk's haki because that's what the plot requires of him.
Wrong about Kaido and Luffy, in more ways than one.
We could say they had equal haki at start. Then Kaido drank sake and his haki became stronger, as impossible as it is technically.
Then, Luffy achieved growth and Awakened and his haki also became stronger.
Whether they arrived at equal haki again at that point is complete guess work.
One thing is certain, Luffy didn't win that clash because he was stronger physically, because Kaido literally matched him for couple of chapters. The raw power was equal and there was no sign of haki being used from Kaido's side in the first place.
The reason why it went into Luffy's favor ultimately is just narrative decision to bring an already dragged-out fight to a conclusion.
My own headcanon is that Kaido also reached his stamina limit in that moment as he was constantly drained from lifting Onigashima.
Exerting himself into Blazing Bagua in that moment has pushed him to the limit and after equaling Bairang Gun he reached his limit and was overpowered.