I'm almost understanding you.
But it is all plot. Kaido and BM are portrayed as monsters that kill a bunch of people. Yet they don't kill anybody on screen, only flashbacks or offscreen.
One Piece ending in 1 year with Akainu just shows how everything relates to plot since currently Akainu can't do nothing onscreen. Only flashback or offscreen. Besides killing Ace of course.
Well yes, it’s plot,

it’s through plot that we build our case for characters portrayal, Kaidou should have joined Baki, Berserk or some shit, his loss, and the plot decided to remove Kaidou and Big Mom out of the possibility to compete in the final chapter like they were some kind of Doflamingos, specifically it’s plot vs expectations (regarding Kaidou and how he failed to meet them up), and Oda decided to clown Kaidou+Big Mom with an alliance of disorganized fledglings, he didn’t even need the strawhat alliance he made in Dresrosa, or his connections with Shanks/Dragon what the fuck. Luffy’s goal is to reach Laugh Tale, not becoming the strongest person that has ever existed, having him beat Kaidou 1v1, not even at the very end of the story, completely humiliated Kaidou, and will force Oda to power creep him, to keep the engagement rate going, like straight up, Kaidou and Big Mom were the two strongest yonkous after Whitebeard, and now I’m supposed to believe that some cripple like Shanks, or Blackbeard, who couldn’t even activate haki last we saw him, couldn’t face Magellan and ran away against Akainu even though he had his ENTIRE crew with him will be a more dangerous opponent than those two combined, fuck that, this arc is the burial of the Yonkous, fans tried to cope with the Sickbeard meme, but Whitebeard was the only yonkou that mattered, yeah, he’s got fucking heart attacks, but so what, Shanks lost an arm, Kaidou is a drunk ass that can’t even hit people properly when drunk, and quickly abandoned his facade of the drunken style when he saw that Luffy was pummelling him, and Big Mom has a collection of weak points to exploit, they’re all pretty much disabled, I will definitely not like it when Luffy gets away scot free at the end of One Piece, still, even if Usopp were to no diff Akainu off screen, he’s exiting the story in better shape than Kaidou, no question asked.