So, you are saying that it is wrong to eat fat & carbs in the same diet, but protein & fat is all right, is that it? Do you know what is wrong with that? Any diet that excludes any one of the major components (fat or protein or carb) is going to throw you off balance after a period of time.
Your low-fat diet worked for YOU. There are people who don't want to, or just can't, eat that way. Also, how do you describe the difference between moderate fat and low fat? What is moderate for me may be too much for you, and vice versa.