You got Naruto who is a hard-working kid that wants to become a Hokage and faced many hardships along the way, the same goes for Zoro, he trained and faced many different enemies along the way, show good leadership and charisma, strong willpower, etc. Naruto got huge power-ups to win against strong enemies, nothing wrong with that. It's just a classic Shounen cliche. Having CoC won't regressed Zoro as a character by any means since he's already proven that he earned it by beating his enemies and having valuable traits. What makes One Piece to be like Naruto is forced parallels, for example, Naruto - Kakashi - Jiraiya, Sasuke - Obito - Orochimaru, Sakura - Rin - Tsunade, Luffy - Roger - Joyboy, Zoro - Rayleigh - Ryuma, something along those lines.