I feel like these are silly comparisons. Kaido isn't a swordsman, Zoro being able to break through his skin with a high enough Ryo is super impressive, but is NOT a measure of swordsmanship skill. King has a meito and could have that same level of Haki, we couldn't know yet because neither Oden's or King's blades are black.
I mean virtually everyone can seemingly hit Kaido. Hes not THAT fast unless he means to be. Its a matter of hurting him or not.
Aka, just because Zoro can cut Kaido does NOT tells us he surpassed Kaido's number 2 due to 1 feat. Its kind of a blind and silly comparison to make. In fact, it's not a comparison at all. And this is a Zoro fan telling you this right now.