imo everyone would be dead by now, sanji wouldn't have been able to protect luffy and the other supernovas like zoro did, also he can't hurt big mom
This.
Nothing else to say.
Sanji could never stop Big Mom and Kaido's combined attack. If Luffy couldn't and neither Kidd ("Thank you Zoro for saving us!") nor Law or Killer ("We cannot do a thing!") could. And Sanji is massively weaker than them.
Sanji could never overpower Kaido's Tornado. He is too weak to do that.
Sanji could never even remotely dream to give serious damage to Hybrid Kaido like Zoro did.
Hell, Sanji is still far weaker than Pre Udon Luffy, who failed to damage Human Kaido, let alone Hybrid Kaido.
Sanji could not neutralize Prometheus as well.
Keep on mind that I am not saying that Sanji is weak. He is not at all, he is strong, with the RS he reaches the level of YCs like Cracker or Jack which is good for someone that a few arcs ago was being humiliated by Vergo and then raped by Doflamingo.
It's just that Sanji pales in comparison to the "strongest pirates of the new generation", who are on a completely different level to him. And Zoro is (bar Luffy)the MVP among them; so do the math.