you yourslef said RS is nothing special and not big of a powerup and Sanji didn't overpower his "germa" brothers and didn't held a candle against Doflamingo who is YC level and had a reasonably good fight fight with Vergo which puts him in veteran level...now with RS he touches YC range and if he beats King with just that it means "King is nothing special" you are using Sanji beating King means Doffy > Katakuri (which is not true but that is for another story) for Sanji vs King and I am using the same where you are contradicting your own logic
Except my logic for this debate is that Doffy is above YC1, so him beating an already YC level Sanji is very plausible. And secondly, I thought you guys put Vergo as very close to YC level. Most Sanji fans believe that Sanji would've won against Vergo if the fight continued.
So, let's take those two things and combine them. We get that Sanji was already YC level in Dressrosa.
But let's come back to the present and try it your way. First, how strong do you think King is? Is he weaker than Smoothie? Or is he stronger than Smoothie but weaker than Katakuri?
Cause even if King is weaker than Katakuri, he is still YC1 (or do you think he is YC2?). So, Sanji with RS, which is insignificant, is YC1+.
Logic dictates that Sanji without the RS is at least YC2. What was Luffy at the beginning of WCI? YC2 or YC1?