It could be due to personal biases. For example, if a writer has a strong dislike for the relationships or actions of Naruto, Hinata, and Sakura in the original series. They might also be influenced by the opinions of others in the fan community and start writing bashing fanfiction. Additionally, some may do it as a form of stress - relief, although this is not a very positive way, by venting their negative feelings towards these characters through writing.
Some people might write it because they prefer other characters over Naruto, Hinata, and Sakura. They could be trying to promote their favorite characters by putting these three down in their fanfiction.
One reason could be that they have different interpretations of the characters. Maybe they didn't like how the characters were developed in the original story, so they use fanfiction to express their dissatisfaction by bashing them. Another possibility is that they just want to create controversial stories to get more attention for their fanfiction.
Chapter 197 is the strongest chapter-level answer because it starts from Seeing that no one cared about what she said, Su Yinwan immediately felt... and follows through on Wen Jiaojiao, aren't you underestimating me?.
The best chapter pointer here is Chapter 199, "You Found Out Long Ago?". It opens with Damn, the production team is actually being so generous this time, giving... and closes on You knew all along?" Zhao Lang adopted a contemplative look before curving....
A practical answer is Chapter 154, because it turns the idea into a concrete scene. The chapter opens with Hahaha, I'm dying of laughter, Lili, do you really have to be so blunt?"..., adds pressure through It stated two clear characters—"Jiang Li., and ends on Helplessly, Director Sun could only.
If you want the clearest chapter reference, go to Chapter 200. Early on, Shang dismissed the thought of turning around and walking away.; later, the chapter leans on The PD had already come over, and with the camera rolling, walking away....
A practical answer is Chapter 169, because it turns the idea into a concrete scene. The chapter opens with Everyone: "What?!" Seeing the shocked and bewildered expressions on their..., adds pressure through If you signed up, be ready mentally.] [Exactly, supporting the sister..., and ends on Wen.
Chapter 154 is the strongest chapter-level answer because it starts from Hahaha, I'm dying of laughter, Lili, do you really have to be so blunt?"... and follows through on Helplessly, Director Sun could only grit his teeth and add another 5....
Look to Chapter 167 for the clearest answer. It begins with By the experimental field, Qi Tianyu was quite helpless as he watched Wen..., keeps building through He tried once again to pull back his suitcase, but to no avail, as one end..., and lands on Even when getting into the car, Qi Tianyu was.
The best chapter pointer here is Chapter 158, "It's Time to Recruit Someone Who Understands Mysticism to Work Here". It opens with Reluctantly, Jiang Yan had no choice but to forcibly join the group for... and closes on we're just very close friends." Sister Li had a vast number of followers....
The best chapter pointer here is Chapter 148, "None are Normal". It opens with Exiting the cottage, Director Sun picked up the phone. and closes on Just as Jiang Li put down her chopsticks, she received the call from Mr..
The best chapter pointer here is Chapter 160, "The Mushroom-Picking Party of Six". It opens with As the sky gradually darkened, the originally mild drizzle began to... and closes on Then came Shu Yan and Jiang Li, while He Yun silently moved to the back of....