Oda uses Zoro for fanservice.
mfer refuses to let him do more than aura farm.
Wano had three Acts.
Why couldn't ONE be dedicated to Zoro? He was there on his own for a while. He literally visited the land of his ancestors.
It's just absurd to me Sanji got all this setup all the way from Baratie, and we've still got mysteries left to solve, but Zoro has to do with scraps in SBS.