I am not saying shanks can't be stronger but using what happened during MF where Kaido only had king and Kaido's portrayal was intact proves it wasn't a win for shanks when talking about power level.
You're missing the point.
kaido has shanks in his top 5. Meaning, he respects him enough to put him there. Kaido only respects strength. So, for kaido to have shanks in such high regard, kaido saw something when they met. Kaido didn't put him there because of his combined crew strength. Individual strength is what kaido respects.
As far as we know, that's the only time they met.
And it wasn't just shanks giving kaido some booze to fuck off, or shanks telling kaido that Nika will come soon or something like that.
For kaido to respect shanks and put him along with legends and lolden, shanks had to show his strength and make an impression on kaido.
Thus, kaido putting shanks there means shanks is >= kaido.
So, kaido meeting shanks once, potentially clashing, and then kaido putting him in top 5, is huge huge portrayal. And I don't see how that's not counted as a W for shanks.
It's not an L for kaido. But it's still a W for shanks because of the implications of the portrayal he got from Kaido placing him along side Rocks, Roger, WB and also PTSD lolden.