Yes, Zoro's Attack was greater than Combined Attack of Four Scabbards (3 of them were Strongest Scabbards along with Neko)
What people fail to see is that Big Mom warned Kaido to dodge, does Readers grasp how crazy that is??
It means Oda didn't only want to Draw Kaido being Careful against that Attack, he completely made a Separate Yonko worry about him!
And it's not like she feared for him getting Injured, it's what he wants after all & i'm pretty sure both of them believe they can Solo them.
So Big Mom wouldn't care if Kaido is slightly injured, she can just handle them herself (From her Perspective)
But Big Mom's Warning + Kaido's Worried Face + BM's Statement that "He underestimated Zoro" clearly shows that Yonko were in "Danger" & an attack from Zoro can cost them the Whole Battle.
Not to mention that other Supernova are already showing their Best or Second Best Attacks (Most of them are New Attacks)
But Zoro is merely using an Old Technique and look what happened.
IMO this Scene leads to only One Conclusion, Zoro now must be Distracted, that's the purpose of that Scene, it's to show us that Zoro have the Power to end this Fight and he cannot be allowed to attack them again, so i expect that in upcoming Chapters he will be Distracted by something, which will leave Room for Luffy to have his Solo Fight & then Zoro will return to End the Battle with him