Maybe they don't like fanfiction in general. It could be that they prefer the official, canon Naruto story. Fanfiction can vary greatly in quality, and they might have had bad experiences with some poorly written Naruto fanfictions in the past, which made them dislike the whole concept of Naruto fanfiction.
The OC could be so focused on their own story within the Naruto universe. They are born into this world with their own goals, dreams, and relationships. Fanfiction might seem like a distraction or an unnecessary addition to what they already have going on. They want to live out their own Naruto - inspired story without the interference of fan - created stories.
They can simply respect each other's preferences. The OC can choose to avoid fanfiction discussions and events while the enthusiasts can respect the OC's stance. For instance, in a Naruto - themed community, they can have separate areas or topics for those who like fanfiction and those who don't.
One possible reason could be past decisions made by Sarutobi that Naruto didn't agree with. For example, Sarutobi's handling of the Uchiha situation. Naruto, who values friendship and fairness deeply, might have seen this as a sign of Sarutobi's inability to do what's right, thus leading to his distrust.
One possible reason could be that in this fanfiction, Jiraiya might be preoccupied with other important matters. Maybe he has a secret mission that demands his full attention and he simply doesn't have the time to train Naruto. Another reason could be that there is some sort of conflict or misunderstanding between them that prevents Jiraiya from taking Naruto under his wing. For example, Naruto might have unknowingly offended Jiraiya in some way, or there could be a prophecy or external force that is keeping them apart for the time being.
One possible reason could be that he has seen the darker side of the ninja world. Maybe he witnessed too much death and destruction during his missions and decided he no longer wanted to be part of it. Another reason might be that he has other dreams that he realizes are more important to him than being a ninja. For example, he could have a passion for art or music that he wants to pursue instead.
One possible reason could be that he gets injured right before the exams and is unable to participate. Maybe he was on a mission that went wrong and he has to recover instead of taking the exam.
One possible reason could be past betrayals. Maybe he has been let down by people he thought were friends in the fanfiction world. For example, if someone he trusted shared his secrets which led to him getting into trouble.
Another reason could be that in this fanfiction, the plot is set in a way that there is a new training system in the village. And this system doesn't involve Kakashi in Naruto's training. There could be new mentors or a completely different approach to training young ninjas like Naruto, which excludes Kakashi from the equation.
One possible reason could be the fear of losing his loved ones. In the original Naruto story, many ninjas sacrifice a lot, including their lives. Naruto might have seen this and decided he doesn't want to put himself in such a position.
Maybe he discovers other dreams or goals. He could find that there are other ways to protect the village and his friends that don't require him to be Hokage. He might be more interested in exploring the ninja world, learning new jutsus, or even teaching the younger generation about ninjutsu rather than taking on the political and leadership role of Hokage.
In the fanfiction, it could be that Sasuke's unyielding thirst for power and his disregard for the consequences of his actions on those around him are reasons Naruto doesn't forgive him. Sasuke was so focused on his own goals that he often trampled on the feelings and safety of others, and Naruto, who is all about protecting and connecting with people, may find it hard to forgive such self - centered behavior.