Perhaps the writer wants to create a unique spin on the Naruto universe. By making Sakura look like Kakashi, they can introduce new storylines and character dynamics. It could also be a way to show how characters can be influenced by each other in unexpected ways. For example, if Sakura starts to look like Kakashi, how would her relationships with other characters change? Also, it might be a form of character development exploration where Sakura takes on some of Kakashi's more positive traits to become a better ninja.
There are several possible reasons. Firstly, it could be a creative experiment. Writers often like to mix and match character features to see what new and interesting stories they can come up with. Secondly, it might be a way to subvert the expectations of the readers. Since Sakura and Kakashi are quite different in the original series, changing Sakura to look like Kakashi can shock and intrigue the audience. Thirdly, it could be a means of exploring themes such as identity and transformation. If Sakura looks like Kakashi, she may have to re - evaluate who she is and how she is perceived by others. This can add depth to her character and the overall story.
Yes, there might be some fanfics out there where Sakura is depicted in a way that she has some similarities to Kakashi. Fanfic writers often like to play with different character traits and appearances in their creative works.
Perhaps he thinks fanfic undermines the integrity of the original Naruto story. The official story has a certain narrative and character development, and fanfic can deviate from that significantly. When it comes to his connection with Naruto, any deviation in fanfic might be seen as a negative. For example, if a fanfic changes the way he mentors Naruto, it could be something he wouldn't like.
In the fanfiction, Kakashi might fail because of external pressures. For example, he could be given other important missions that take up a lot of his time and energy. So, he can't dedicate enough time to Sasuke and Sakura's development. Also, he could be facing political pressure within the village that restricts his teaching methods or the resources he can use for their training. This would lead to him not being able to meet their needs and ultimately failing them.
Another plot could be that there is a traitor in the ANBU, and Kakashi and Sakura are tasked with finding out who it is. They have to investigate their fellow ANBU members, which is difficult because they are all supposed to be highly trustworthy. During this process, they might discover some secrets about the ANBU that they didn't know before, and their relationship might change as they uncover more and more about the mystery.
Perhaps in a fanfic, Sakura could mimic Kakashi's reading habit. So she's always seen with a book in hand, and this new habit could lead to some interesting interactions with other characters. For example, Naruto might be constantly curious about what she's reading. And it could also be a way for her to gain new knowledge and skills in a more Kakashi - like way.
One interaction could be that Sakura is initially a bit intimidated by Kakashi's reputation, but as they work together more often, she becomes more comfortable around him. Pakkun, on the other hand, might be very protective of Sakura. He could growl at Kakashi if he feels that Kakashi is being too hard on her during training. And Kakashi might just chuckle at Pakkun's protectiveness and respect his loyalty towards Sakura.
It could be because of a dark power corrupting Sasuke. Maybe an ancient evil force takes over him and makes him see Sakura as an enemy. In some fanfics, this kind of external influence can completely change a character's actions. Also, it might be related to Sasuke's pursuit of power. If he believes Sakura is standing in the way of his ultimate power - seeking goal, he could be driven to kill her.
It could also be that Naruto is forced to leave Sakura due to some external threat or danger. For instance, if there is an enemy targeting Naruto and he fears that being around Sakura will put her in harm's way, he would choose to leave to keep her safe. This is in line with Naruto's selfless nature as seen throughout the series.
Maybe to explore different character arcs. The writer might want to see how Sakura would develop as a character if she strayed from her loyalty to Sasuke. It could also be a way to introduce new characters or relationships into the Naruto fanfic world.
One possible reason could be Sasuke's focus on his revenge. His thirst for vengeance against Itachi might make him blind to Sakura's feelings and neglect her as he is constantly preoccupied with getting stronger to achieve his goal of revenge.