Is it as much of a dystopian nightmare as, say, having no food at all?
Yes. Having every man, woman and child line up for government potatoes, government bread, and government cheese at some government office is unequivocally a dystopian nightmare.
There's also no reason that distribution has to work that way. How about an EBT card mailed to every home, which can be used for potatoes, cheese, and bread at any grocery store?
It's also a strawman because not everyone would be lining up for potatoes in this instance, presumably some people can afford to eat in this free suds world. Maybe we'll even have a post-potato society eventually, when everyone decides they hate potatoes after they all get jobs (probably not).