User blog comment:Fliu/The Reasons Big Mom Has To Go Down/@comment-24769684-20170313015350/@comment-24769684-20170313033140

Kizaru acknowledged that he was caught off-guard by the attack. It wasn't effective, but it did demonstrate that, just like in the real world, even the strongest of people can be caught off-guard with the right moves.

Jinbe wouldn't be around to protect Fishman Island because he'd be a member of the Straw Hats. Right now, the protection of the Straw Hats would not be comparable to the protection of a Yonko. You see now how pirates fear to cross the line in Fishman Island at the mere name of Whitebeard or Big Mom. Luffy does not have that kind of authority or power right now.

Right now, Blackbeard seems poised to be the final villain of the series and the final obstacle Luffy faces in his path to becoming pirate king. Marine Admirals serve as an entirely different threat than the Yonko do. If Luffy takes one of them out, he's just chopping off the head of a Hydra. But taking out a Yonko has much larger consequences involving the struggle for territory and power as I said above. Such consequences would not be gained from the Kaido fight if Big Mom had already been deposed beforehand.

I don't know what kind of role Big Mom will ultimately play in the story, but the role of final boss many people are expecting her to have will not only remove most of the stakes of the Kaido battle, but also bring on a storm that will likely be too big for the Straw Hats to handle right now.

Also, the Totto Land arc is supposed to end this year. I'd be highly skeptical that both the wedding ceremony and the ultimate deposal of a Yonko would end in a remotely timely fashion.