The natural course of Crohn's seems to be to try to destroy your quality of life. Not all the damage that can be done is reversible.
Failure to absorbe nutrients, emergency surgery for abcess or stricture, fistulas, extra-intestinal manifestations, clots, etc.
I have no doubt that this disease needs to be treated by SOMETHING, diet or meds, diet and meds, whatever, but the natural course of Crohn's is not pretty.