Kaido has also been blitzing Luffy. Until that magically stopped.
Its funny how you believe that Luffy can go from being absolutely bodied by a base move of Kaido in a 1xX to end up fighting him on more or less equal terms in a 1v1, but somehow Law can not. Or Zoro. Or Kidd. This is where you heavy bias comes in.
Its unimportant whether Kaido got knocked out or not. BM was also not knocked out and lost.
This is some damn stupid Luffy fan power trip and nothing else.
Reality check: Luffy was at the mercy of Kizaru and had to be force fed to even survive