I think you guys are getting a bit out of place with the whole power scaling overthinking.
First of all, hurting Kaido is simply the starting point and pretty much the basic if you want to even face him. That's still far from actually taking him down or even being a threat, he's still one of the most powerful characters in the whole world and the Scabbards are probably bound to fail.
And second, the narrative here is what it is: it was very unlikely that Oda would write this arc without the Scabbards shining versus Kaido at some point. I personally don't like this, but because of how Oda is handling the action and not the events themselves (this RPG structure doesn't work for me). Kaido was introduced from the start in contradictory ways, being both invincible yet with one of the highest defeat records to be explicited, and his role as the great oni in the Japanese arc likely connects with Shuten douji and, therefore, with the tale of a group of samurais going after his head. Even if Shuten douji isn't the character Kaido is based on (his flashback will clarify this), the idea of the warriors facing the big demon and not being completely annihilated was arguably a must in the context of Wano, so Oda wouldn't miss it only because some fans would start talking about Yonkotards, Mihawk one-shotting Kaido, admirals being stronger and so on. He's a writer first and foremost and would hardly miss the opportunity of drawing such scene, in my opinion.
So that's pretty much it. Let the guys have some moment like in traditional Japanese legends without going nuts over power scales because you're losing your time thinking this says anything about who's stronger or not: it more than likely doesn't at all.