I have to come out of my hiatus and state on this matter coz seems like people are kicking a dead horse at this point
The necessity of zoro fighting someone has always entailed a prerequisite hype and suspense which overall makes sense, this in turn pushes zoro to do more against high caliber opponents.. that have a certain notoriety to them.
Now the problem is
i don't see how zoro can even remotely replicate the hype and the growth on the roof against someone like king.. with him out shining his captain on the roof against a yonko albeit with solid assistance..So the rooftop has killed any and every lingering glamor and depth this 1v1 had.. its because not only would it make no sense when you take his condition into account, it would be an irrelevant fight for zoro that won't even narratively develop him at all.
in a nutshell
1)his condition
2)narratively irrelevant fight for zoro
3)growth would be miniscule
4)a formality.. that would make zoro monotonous in Onigashima