Yonko level luffy wouldnt get wasted by a drunk ass kaido and then come back top tier a few days later.
Luffy has suffered from PIS nerfing many a time and didn't get a chance to use future sight, snakeman or tankman.
Kaido sobered up to one shot him, and he one shot Oden who was on his level 20 years ago before he gained more strength, so Kaido one shotting someone doesn't mean he is astronomically so far above someone that a turn around is impossible.
Luffy was on katakuri's level (not as strong obviously, but on the same tier of strength) coming into WCI
if we remove the FS haki hax that is what makes Katakuri freakish. Once Luffy had that he could fight.
Similarly he couldn't fight against Kaido because of his scales, now he can, and in fact he leapfrogged past the level of being able to damage him, to being able to do levels of CoA that no one else apart from hakimen freaks like Rayleigh/Shanks/Garp can replicate.