I do think you are confusing drawing with point-of-view or personal expression. Drawing can be taught (although it is a life long pursuit), point-of-view is much more a personal journey. Drawing is something you never completely learn, but you can technically master aspects of it. Point-of-view has much more to do with what you know and how you look at the world.
The lines get blurry when drawing is effected by point-of-view. You mentioned Schiele, I believe to be one of the greatest drawers ever. His drawings were very personal and I agree you can't teach what make his drawings great, you can only encourage! I also agree that the environment and the information students are exposed to is extremely important.
As in Schiele's drawings, personal expression becomes the most important aspect of what makes an artists work great! You can technically be a great drawer, have nothing to say and make uninteresting images. This is a battle that has raged on for centuries and will continue. It come down to, you cannot quantify all aspects of art!
I don't think we are arguing.