It goes without saying that drawing is a way to represent 3D objects into 2D space.

Once the fundamentals are good - i.e. "accurately reproducing a 2D perspective projection of an anatomically correct 3D horse from any angle", you could develop your own style, make caricatures, cartoons, hyperrealism, figurative-expressionism, etc... You can have the freedom knowing that your skeleton (figuratively speaking) is correctly placed in 3D.