Why do people keep saying "the body can't differentiate between calories" and "a calorie is a calories, how can the body know?" and other such nonsense?

As if the body were some barely evolved dumb machine and must conform to rigid human logic.

Without exercising more than a few brain cells we know it is senseless; when you eat a calorie of carbohydrate the body knows the difference and processes it differently than a calorie of fat or a calorie of protein. Ever heard of insulin? Obviously the body does know the difference.

Please stop the madness. Thank you.