What you're failing to grasp is that sometimes some people are just superior to others. It's the rules of nature. Wee-Man from Jackass can dedicate every second of his life training and fully maximising his body. It would be admirable, but he is still never beating Lebron in a 1v1 basketball game, Mike Tyson in a boxing match, Usain Bolt in a sprint
Sanji is just superior than Zoro. Get mad and say it's unfair all you like