[Inky]

This thread reminds me of a silly children's series called "Tales of the Dark Forest", in which the Forest had gradually taken over the world, so now it was just a walled city in the middle of an endless forest inhabited by fairy-tale monsters of all kinds, which nobody with any sense ventured into, and nobody knew what had happened to the other cities. It wasn't meant to be sensible, so they didn't bother to go into where Dun Indewood got its food from. But if you were going to make Create Food widespread, a town in the middle of a wood with no visible means of support would work perfectly well.

One possibility I'm picturing is that it requires some kind of ambient magic, possibly generated by living things such as the forest trees, which is used up by casting the spell but renews itself over the course of a day (or other length of time if that gives interesting results). That would put a limit on how much you could create at a time. Depending on the parameters, you might end up with a spell that would make food no problem to a traveller (who'd be moving to a fresh patch of forest every day), but make hardly any difference to a town.