That lowers the efficiency of the whole system, meaning less gets done altogether. Quoting TV Tropes: "In truth, some countries have a relative productive advantage in some areas, while other countries have different relative productive advantages. Trade allows countries to specialize in whatever production they have an advantage in, thus producing more in total, and then trade with each other. This makes both countries better off. For example, perhaps Country A can produce 4 cans of butter, or 2 cans of butter and 1 carton of eggs, or 2 cartons of eggs. Country B can produce 4 cartons of eggs, or 2 cartons of eggs and 1 can of butter, or 2 cans of butter. With trade, they can produce at their advantages of 4 cans of butter in A and 4 cartons of eggs in B and then trade so they each have 2 cartons and 2 cans. Making them both better off than if they produced everything in their own country."