In practice importing diminishes options, both for the locations that find their market flooded with the standard supermarket-optimized foods, and the for the poor countries that are compelled to make their land produce the "best" for the sake of profits. In the last century 75% of crop diversity was lost, and in the decades after the Green Revolution poor countries became net importers of food. Simplistic logic that looks at effects completely abstracted from the system, would make such outcome look impossible.