We saw that physical strength from G4 does nothing by itself except moving Kaido around.
The key is haki and his haki is the same in base and G4.
So even with perma G4, he would still deal the same damage since the tossing Kaido around does nothing.
Inconsistency or not. You can't deny that Adv COA is a prerequisite to be able to use this form of COC. The first time advanced COA is demonstrated by Hyo, he blasts Alpacaman with a shockwave without making contact with him. It's more likely that there are more ways to use the concept of flow than having it not touch all the time. Even the diagrams Hyo show and Luffy's punch to the tree are fairly consistent.
The act of not touching has been signaled as an ADV COA thing. It's only more evident/noteworthy when you mix it with Conquerors because again, Ragnarok and Thunder Bagua are Adv COC attacks yet, they make contact unless ADV COA is used.
Even if you find an inconsistency in that all of this the main point remains.
To Coat yourself in COC you must know ADV COA because it is about the concept of letting Haki flow. Without it, you can't do what Luffy, Kaido, Linlin, Roger/WB have done.
The internal penetration of ACOA (Ryou), is already exaggerated for anyone other than KAIDO or BM, in fact ACOA will mess with (cause serious damage, in other characters) them, but the simple fact that you need to combine ADCOC and ACOA to try to cause damage that are effective in KAIDO at the end of the day, already makes KAIDO a step above other ADCOC users in terms of difficulty in defeating it. That is why those who do not (do not have) ADCOC are more likely to hit someone like SHANKS, rather than KAIDO.