Oxycontin is perfectly legal and regulated such that only qualified professionals were able to prescribe and dispense it. And look how that turned out.

There's a whole lot of evidence that prohibition vs legalization each have negative effects and it is up to society to decide which is more appropriate in certain situations.

I doubt that food regulations are going to result in black market Doritos barons waging deadly turf wars in the streets. But I suspect it will result in food manufactures building a much worse product in response.