You think if Sanji has ACoC as well as PoL that allows him to bend the laws of physics on top of his genetic mods there'd be balance between him and Zoro for instance?

. If Oda's gonna give Sanji CoC on top of a broken ability like PoL then Oda's gonna have to balance it somehow with a black blade for Zoro or something otherwise pending that there'd be an imbalance.
It's the same reason why Shanks is at a higher level than either Kaido or Linlin Haki wise, otherwise those two would just be outright stronger than him. In the same vein Roger's Haki was most likely at a higher level than Newgate's.
Also as strong as Sanji is, he's the No.3 of the SHs, Oda has to limit him somehow, he can't just take off the lid like he did with Newgate. Sanji's not competing with Luffy.