Because ZKK tries to overshadow Luffy at his own goal of taking down the yonko and becoming pirate king.
BIG NEWS "Luffy beat the shit out of Kaido" Bounty increase to 5.6 billion
3rd page news "Luffy's subordinate Roronoa Zoro killed Kaido" Bounty increase to 2 billion
Doesn't quite sit right.
Sanji vs King is ultimately two flying fire kick user subordinates beating each other up, nothing is stepping on anyone's goals.
BIG NEWS "Luffy beat the shit out of Kaido" Bounty increase to 5.6 billion
3rd page news "Luffy's subordinate Roronoa Zoro killed Kaido" Bounty increase to 2 billion
Doesn't quite sit right.
Sanji vs King is ultimately two flying fire kick user subordinates beating each other up, nothing is stepping on anyone's goals.
Luffy is most likely not defeating Shanks for example. And there's Big Mom too on that rooftop, he doesn't have to necessarily defeat both yonko on his way to piratekingship I mean. (Also who the hell said it's mandatory he defeats all yonko for that to happen).
I'm annoyed by people who never consider things from a broader perspective out of commodity (Eventually).