Based on the adult manga by Imonet Satsuki.

Why do my art teachers hate it when I draw anime? What’s wrong with it?

It’s not so much that you’re drawing anime, it’s what you’re not drawing that concerns them.
Learning to draw includes training your eyes and your hand to create a representation of what the eye sees and the brain wishes to make.
Drawing from life is one of the most influential things you can do to develop skill.
It’s a necessary baseline to other forms of art.
Learning to draw from stylized drawings rather than life can be detrimental to you developing your abilities. Let me illustrate.
You might be familiar with Pablo Picasso.
Here’s one of my favorite pieces of his, Guernica: He has a very distinct style, doesn’t he? And it doesn’t look like it would be terribly difficult to learn.
You could practice for a few months and crank out some Picasso-esque artwork. What about this? This is also a Picasso, and he was only 15 years old when he painted it.
Do you think you could practice for a few months to make something like this? It would probably take you much longer, with many lessons and much practice. Now, here’s the trick.
You could crank out a piece like Guernica without the classical training.
But it wouldn’t be as good.
You see, Picasso’s understanding of volume, form, line, shape, shadow, perspective, the human form, etc., were all used and deliberately manipulated as he worked his way towards Cubism.
Without his initial understanding of drawing and painting from life, we likely wouldn’t have seen the rich body of work and influential styles that came later. The anime artists you admire likely also know how to draw from life, and that definitely influences the quality and versatility of their drawings.
So go outside, draw some trees, streets, buildings, birds, cats, etc.
Learn to use your pencil set.
Draw your friends and family.
Draw cups and mugs on tables.
Draw hands.
And as you draw, look.
How dark are those shadows? Are your angles correct? Are the proportions of the head and body you’re drawing accurate? Learn.
Then, when you are tired of that, doodle some anime too.
You’ll be surprised to see that the more you study real life, the better your cartoons will look. One final thought: It’s quite possible that your teachers may feel that their students’ interest in anime will most likely fade.
I watched and drew anime when I was younger, but eventually lost interest in it.
They don’t want you to devote so much time to a style that you may eventually abandon, and may want to ensure you’ll have skills to keep your interest in art alive beyond that point.