Where were those pairs when Zoro went to rooftop.
When Zoro became WG.
When Zoro took all of Luffy's pain rather than sharing it with Sanji.
When Zoro got CoC.
Or where's the pair in Roger Pirate parallel of Gold, Silver and Bronze. I just see a trio in proper hierarchy.
Kidd/Killer, Smoker/Tashigi, Coby/Helmeppo, Crocodile/Mr.1, Lucci/Kaku, Garp/Bogard, etc all parallel Zoro/Sanji as pairs, right? Oh wait...
Yeah, no. Zoro and Sanji has some parallels as pairs because they're Luffy's right and left hand men, two biggest pillars of support and wings. But the narrative has made it very, very clear dozens of times that Zoro ultimately stands out as the strongest and most prominent pillar. Be it through his other parallels with Luffy, and there are many, or through his own exclusive portrayal that sets him apart from everyone else.
At the end of the day, it's the M3 and hierarchy of Zoro > Sanji is evident in more ways than one.