If the UBI was just to replace food stamps, then I would tend to argue your side, and even more that it would be unnecessary, as we already have foodstamps in place.
But UBI isn't just hyped up food stamps, it's a guaranteed income for all people. Set at an amount to cover their basics - much more than just food stamps, and creating a much better place for everyone, literally everywhere.
The concepts are very complicated, and we are no where near a time or place to put it into effect (maybe 50 years from now, maybe). But the end goal is to have a society that has eliminated poverty, who only work because they want to, and where everyone's basic needs are covered.
I know it sounds very hoity-toity socialist high road bullshit. But it's a sound idea, highly idealistic, and counts on people wanting the best for everyone, not just themselves.
But the United States (and many other countries) have a long way to go before they are in a place where mentally, socially, and economically, UBI will work. It also relies heavily on automated systems for a plethora of services - including most/all manufacturing, services, etc.
I usually don't link wiki,
but it's a nice general summary - and gives good distinctions between welfare and UBI, along with tech leaps we'll need to actually accomplish it.
Visual Example of UBI:
Everyone get X
People who want more work to get X + Y
And Y are pretty much only high level jobs requiring specifics skills. Because automation will just supress most low level jobs.