Correction: Multiple rounds of Luffy with Oda retconning his df and multiple intervals of rest and plot armor and 4 power ups and 17 other YC level fighters and the handicap of holding an island afloat in the sky and Kaido offering a free hit defeated Kaido.
yes, full of plot armor and all that
and what happened?
Kaido got defeated
it doesn't matter that Oda retconned or whatever, at the end of the day, Oda writes the story
and Oda made Shanks look EXTREMELY more impressive than Kaido and Big Mom with that attack
and everyone alreayd knows that's not Shanks' strongest attack at all
so where that does that leaves us?