All these ppl are getting way too jacked up over the narration box btw
The same narrator announced Kaido's victory
in Enies Lobby, all victories were announced by Narrator but Luffy's fight victory was announced by a random marine.
Luffy's win against Katakuri was announced by Brulee
Luffy's win against Doffy was announced by the colosseum guy,
Luffy's win against Lucci was announced by a marine
Luffy's win against Enel loss was announced by a bell.
We also saw the Strawhats/citizens usually witnessing Luffy's victory in some way in each arc too.
Katakuri's defeat was signaled by whoever came out of the Big Mirror.
Doflamingo's defeat is signaled by Bird Cage disappearing
Lucci's defeat I guess was seen by the Strawhats. Not only that but Aokiji declared the Strawhats' victory when they fully escape the Buster Call ending in Marine's complete defeat
Enel's defeat is seen when his Raigou is destroyed and Luffy makes it sunny. Luffy ringing the bell accomplished the dreams of the Sky Peians and Jayans. Also, Noland's ancestor seeing Luffy's huge shadow.
I don't think Luffy vs Kaido has the same gravitas.
If Luffy defeats Kaido, Onigashima falls. Onigashima doesn't fall and everyone is still alive.
Kaido being fully defeated means his flame clouds dissipate on their own. Raizo's water scroll actually dissipates it.
None of the citizens of Wano have any indication to know Kaido is defeated and it's been emphasized that until kaido's head is taken that he won't be defeated. Even Luffy says that he was going to kick Kaido off of Wano prior to Gear 5 but Kaido is still in Wano.
Too many false flags for Kaido's full defeat.