Why are “food groups” a thing?

The modern concept of “food groups” is honestly pretty silly and arbitrary. There are constant debates on whether tomatoes are fruits or vegetables. Well, biologically speaking, they are fruits, but what is a “vegetable” anyway? Just any edible plant? In that case, all fruits would be vegetables too. Apples are edible plants, as are watermelons. Mushrooms are traditionally called “vegetables” too, but they aren’t plants at all. They’re fungi. But “fungi” aren’t a food group. They aren’t meat by any means, so what food group are they?

And what about grains? What are grains? They’re considered a “food group,” but are they not edible plants as well? What distinguishes corn or rice from any other plant? Fruits, grains, and “vegetables,” whatever that even means, are all edible plants—except mushrooms.

What about plant-based “meats?” Is a soy burger a vegetable, a meat, or a grain?

I suppose meat and dairy are the most concrete and definable. Meat is an animal’s muscle, and dairy is an animal’s milk (or things made from that milk). But then you could ask…is soy milk or coconut milk dairy…or is it a vegetable?

It’s all quite silly and arbitrary. Food is food. 🤷‍♂️