[fogihujy]

If you're in a situation where you would need alternative ways to feed current population levels then foraging will be required even if it's not enough on it's own. It's a matter of adding whatever can be added to the total pool of resources, and not about finding a single source.

Post WWII, didn't just forage, they also rationed food, bred rabbits in parks, went fishing, planted potatoes in their backyards and so on. If any of those options hadn't been available things would have been much worse.