I personally would choose grass fed beef or bison or chicken, multiple steamed or roasted vegetables and I would not add salt, ketchup or salad dressing. And no soda.
In that case, the food is of much higher quality than anything I can buy at McDonalds.
But the burger is certainly food according to anyone's definition. Get a quarter pounder with cheese and tell me how that's nutritionally any different from a burger you make at home with standard supermarket ingredients -- ground beef, hamburger bun, american cheese, ketchup, pickles, onions. Yet nobody complains about that at a neighborhood, family or church cookout.
You are correct that I could buy and eat that stuff at home, but like I said, I could also buy Doritos, coke, sugar rolls, candy, etc. etc.
It's no closer to food than Doritos or Coke are.