Some fanfiction writers might do it to explore darker themes. They want to show how a character can grow despite such a difficult start. In these stories, Naruto's family abuse could be a way to introduce complex psychological aspects. It could also be a way to contrast with the more positive relationships he forms later, like with his friends and mentors.
Another reason could be to deviate from the original story in a radical way. The original Naruto series doesn't have this family abuse plot. So in fanfiction, writers might use it to put a new spin on the character. They may think that by adding this element, they can attract readers who are interested in exploring different interpretations of Naruto's character development.
A possible reason could be jealousy. If Naruto had a sibling who was always favored by their parents, he might grow to hate his family. He would feel like he was always in the shadow of his sibling and that his family didn't care about him as much.
Perhaps in the fanfiction, Naruto is exposed to a new philosophy or way of thinking that promotes forgiveness. He might meet a wise character who teaches him about the power of forgiving one's family. Also, if Naruto experiences a similar situation where he has to make a tough choice that might be misjudged by others, he could then understand his family better and forgive them. It could also be that Naruto finds out his family had no other option in the situations they were in, and this realization leads to his forgiveness.
One possible storyline could be Naruto gradually finding his inner strength despite the abuse. He might meet a mentor figure who helps him see his own worth and start to stand up to his family. Another could be that Naruto runs away from home and joins a group that accepts him, and then he returns to face his family with new confidence.
One reason could be to explore the darker side of family relationships. In the Naruto world, family is often portrayed in a positive light, and this could be a way to show what could go wrong. Another reason might be to create a unique and attention - grabbing plot.
One possible reason could be a long - held misunderstanding. Maybe Naruto discovers some family secrets that he misinterprets as betrayal or neglect. For example, if he finds out that his family had made some sort of pact that he disagrees with, it could lead to his rejection.
One possible reason could be that he has some unresolved issues from his past, like the absence of his parents during his childhood which made him feel a sense of detachment. Maybe he is so focused on achieving his ninja goals that he unconsciously starts to ignore his family. Another reason might be some sort of miscommunication within the family. For example, if there are secrets that the family has been keeping from him, he might feel betrayed and thus choose to ignore them.
One possible reason could be a divergence in values. Maybe in the fanfiction, Naruto discovers that his family was involved in some dark or unethical deeds that go against his principles. For example, if his family was secretly working with an enemy organization that Naruto has been fighting against. Another reason might be a sense of betrayal. If his family had made decisions in the past that put Naruto in a difficult or dangerous position without his knowledge, he could feel the need to denounce them. Also, it could be due to a misunderstanding. False information might be spread about his family, leading Naruto to believe they are not what he thought they were.
Maybe there was some kind of powerful jutsu or curse involved. It could be that an enemy cast a spell on Naruto's family, making them forget about him.
In some fanfictions, Naruto might abandon his family due to a false prophecy that convinces him he's a danger to them. He may think that by leaving, he can protect them from harm that might come his way because of his past or enemies.
One possible plot could be Naruto's struggle to rise above the abuse. He might discover his godlike powers gradually while facing the emotional and physical abuse from his family. He could start to form his own support network outside the family, like with his friends from the ninja academy, and use his newfound powers to prove his worth not only to his family but also to the whole village.