Food stamps tend to suck for a lot of the same reasons food pantries do. You're still telling people what to buy. It's not as bad because there are more choices, but it's still the same general problem where you have a bureaucracy telling you what to buy instead of being able to buy what you need the most like anybody else.
Sometimes what you really need is food. Sometimes -- or some specific days -- you have access to food and what you really need is to save up enough for a working car or gas to put in it so you can go to job interviews. Or something else that the person in question knows they need but arbitrary politicians have no way to predict.
But if you give people food stamps, they'll buy food with it. Even if they already have suitable food, because it's free money that can only be used for one thing. Then it costs the taxpayer $1 and provides the person with $.05 worth of value, which they take because $.05 is more than $0.
Meanwhile just giving the person $1 cash would give the person $1 in value and cost the government less, because then it isn't necessary to administer a system to force people to buy the thing they needed less instead of the thing they needed more.
And eliminating that bureaucracy reduces the Shirky principle problem.