Fruit is a botanical term for things with seeds in it. Vegetable is a culinary term. They aren't mutually exclusive so when people say something is either a fruit OR a vegetable, it isn't an apples vs oranges comparison.
I mean, that it's a terrible definition of vegetable, considering it rules out a very large amount of vegetables, including tomatoes, bell peppers, eggplants and cucumbers.
You can apply that to pretty much any categorization we make for the natural world.
The natural world doesn't care for our categorizations or social construct. It can, and will, make shit that just does not fit to any of our boxes, and like it!
It's a definition of "fruit": thing that's full of seeds, intended to fall off the plant.
Technically, any part of a plant is a "vegetable". Tomatoes? Vegetables. Lettuce leaves? Vegetables. Leek stalks? Vegetables. Spruce 2x4? Vegetables...
Why should anyone care this much though. It isn’t poisoning anyone. it’s not breaking anything in the kitchen. It’s still edible. No animal died to give it to you.just Eat it and be fed.
Generally when people talk fruits and vegetables they are referring to culinary tradition. Vegetable does not have a precise scientific definition anyway, despite what you've heard from The Big Bang Theory.