It could also be due to personal growth. Naruto might have outgrown the ideals and limitations of being a Konoha ninja. He may have developed his own set of values that no longer align with the village's ninja system. For example, he could have found that the constant focus on missions and loyalty to the village overshadowed the importance of individual freedom and justice on a broader scale.
It might be due to a lack of inspiration. Writing fanfiction requires continuous creativity, and if they ran out of new ideas related to Naruto and the ninja world, they could decide to quit. For example, they might have explored all the character arcs and plotlines they could think of within that context.
For Sasuke, it could be a complex reaction. He has his own issues with Konoha, but Naruto was always a sort of anchor for him. Naruto leaving could either push him further away from the village or make him re - evaluate his own relationship with it.
Perhaps Naruto in the fanfic resigns due to a new threat that he realizes Konoha can't handle in the traditional way of being a ninja. He might think that by resigning and working from the outside, he can find a different solution to protect the village. He could also be influenced by new ideals or philosophies that go against the traditional ninja way in Konoha.
Perhaps Naruto quits Team 7 in the fanfiction because of a betrayal. He might find out that one of his teammates has been secretly working against him or has lied to him about something really important. This could shatter his trust in the team and make him want to leave. Or it could be due to an accumulation of small incidents. Like constantly being the one to get in trouble for the team's mistakes, or not having his opinions heard when it comes to team strategies. Over time, these little things can build up and make him feel that he's better off on his own.
One possible reason could be that he gets tired of the constant fighting and bloodshed. He might have seen too many friends get hurt or die, and it just becomes too much for him to bear. Another reason could be that he discovers a new purpose in life outside of being a ninja, like focusing on family or helping the village in a non - combat way.
One possible reason could be false accusations of a serious crime. For example, if he was wrongly blamed for a major attack on the village. Another reason might be political intrigue. Some powerful figures in the village might see Naruto as a threat to their power and find a way to banish him to maintain their control.
One possible reason could be that he is wrongly accused of a serious crime against the village. For example, if some important secrets are leaked and the village leaders suspect Naruto without proper investigation, they might exile him to safeguard the village's so - called security.
One possible reason could be that Naruto realizes the Chunin Exams have become too dangerous and he doesn't want to risk his life or the lives of his friends. Maybe he sees the dark side of the competition, like how some contestants are willing to cheat or harm others to win.
One possible reason could be fear. Naruto has the Nine - Tails within him, and some in Konoha might be too afraid of its power getting out of control. They may not fully trust Naruto to keep it in check.
It could be that Naruto has other creative or intellectual interests. For example, he might be more interested in art or learning about the history of the ninja villages rather than participating in ninja battles. He could find the rigid ninja training and the constant competition unappealing. Also, perhaps he has a different sense of purpose, like wanting to focus on building peace in a non - combat way, which doesn't require being a ninja in the traditional sense.