It isn’t a reach to say that fully focused Lucci with an awakened Zoan stacking master level Tekkai and CoA on top of that could reach Kaido’s regular durability
Base Lucci with just CoA was able to block a CoA coated strike from 2 sword Zoro with his leg
Mind you, Zoro with just armament made Kaido bleed multiple times
I think Lucci's defense isn't even close to Kaido's dragon scales.
There is no superior durability on Kaido other than his regular durability.
And that has made him a problem for the entire world.
Also, there is a difference between clashing and tanking. Not the same thing.
Kaido has been tanking named attacks from Zoro. Lucci didn't tank anything.
First named attack has defeated him. People got fooled by "fingernails clashing with swords".