Tbh i dont agree. We have nothing to gain from Marco defeating King. Theres no growth, only baseless eye candy which im sure we'll see from a clash. The reason we got so many strawhat fleet fights were exactly that: they became Strawhat subordinates. Marco will likely never be Luffys subordinate, he has a place taking care of WBs island and is not a newer generation pirate
Trust me, there are themes to this manga, an old gen pirate taking out another old gen pirate virtually does nothing for the story. Its why Oda often stalemates those clashes or just never resolves them. They are the old pirates.
Zoro's moment isn't about defeating Kaido, its about hurting him. Luffy will be the one to defeat the Yonko, I feel like thats obvious