Why does the narrator say that the wallpaper commits “every artistic sin”

I do not know if this is a multiple choice question or not, but she says that because she thinks that the “horrid wallpaper” does not conform at all with the traditional rules of art, of good and perfect art.  

Explanation: In this soul-stirring story, the narrator, who suffers from a nervous depression, is writing about the house that her husband has rented for the summer. She does not like the room that her husband has chosen for her, the nursery at the top of the house, particularly the wall paper. She describes it as “one of those sprawling flamboyant  patterns committing every artistic sin,” commenting on its horrendous, hideous, unreliable and infuriating color, and its confusing and torturing pattern. She is so obsessed with it that she even writes that it is as if the paper knew “what a vicious influence it had,” and gets “positively angry with the impertinence of it (she is here referring to a specific area, where she sees eyes and a broken neck) and the everlastingness.” Throughout the text she describes other areas of the house and its exterior, but inevitably she always returns to the wallpaper. At the end, she starts to believe that her health is improving because of the paper. She tears off the paper, assisted by the woman who has come out of it, like her (so she thinks), creeping, and with the hope that she is never put back in it.