I agree that Sanji downplay is stupid and very prevalent, but I'm also not gonna act like I don't see tons of people trying to push agendas that make Luffy miles and miles further ahead of Zoro than he really is while simultaneously trying to ignore the fact that there is a legitimately visible gap between Zoro/Sanji
The special about Sanji has always been that unlike the other crewmates outside of Luffy, Sanji is the only person Zoro cant just Low Diff.