You're basically asking me: why do you think so?
Well, I treated this topic a lot of times so I'll do my best to be brief. The main reason is on a narrative POV, making Kidd be surpassed in damage/spotlight by both Luffy
and Zoro makes no sense narrative-wise, all the hype, competition with Luffy, the way he was always treated in a different way when compared to other SN (he's the only character in the whole manga who had the same path of Luffy even post TS, for example).
Making all this bulid up to end the battle in a Kaido vs Luffy and Zoro? Is the most
boring thing Oda could do imo, such a shonen trope... here we have the chance to make the 2 kings (CoC users) compete just like they were doing in Udon but in taking down the Beast they mentioned when they met
In a nutshell, Luffy and Zoro vs Kaido is boring af
to me, Luffy and Kidd vs Kaido is much better imo.
And nope I'm not stubborn, I keep my stance on Kidd and Killer cause I elaborated a reasonament with both of them and I think I'm on the same wave Oda is, I'm always open to switch ideas if proved with something more convincing than what I elaborated.
Didn't happen as of now tho.