Long ago, in a music theory class, the teacher listened to my composition and said to me; "The assignment was to create a simple classical piece, and you give me Danish Modern!". I didn't know what Danish Modern was, but got the point. When you're a student, they want you to do it their way, and not reinvent the thing they are trying to teach. Once you can prove you can follow instructions, you might be allowed to show your originality, eventually. But, you have to show you learned the basics before you'll be permitted to go beyond that point.
The trick in education, as in life, is to understand what they want, and give it to them to the best of your ability. regardless of your opinion. Your teacher has probably been teaching a lot longer than you've been a student, and they generally know how it's done in the real world. Arguing is usually pointless; it is often regarded as simply an unwillingness or inability to learn. Try to understand that your objective is getting a good grade, not massaging your ego.
Tom