if this was a world like black clover, or hxh then zoro and sanji would prevail. Gon, killua, kurapika all got development in a way that does not make you feel that gon is superior. In black clover zoro and sanji would prevail as well. Asta, yuno are both chosen in a sense, you can root for both of them. Magi has a world such that the mc is not overbearing on the other characters you want to see become string. If you take the characteristics of these characters and apply them in different context, then zoro could reach his potential without luffy being detrimental to his development.

As of now the sentiment seems to be that zoro Along with the others can only be as strong as luffy, while luffy Is free from such restrictions. In this context, Law and kidd are more free then zoro, in terms of development.

the one piece world is different, it does not establish story elements like other worlds.

In this world luffy is main character, similar to other shonens. Therefore he gets main character treatment. Maybe zoro would develop better outside of luffy. Like in other series. Where characters are not bounded to each other.