It's a social ritual thing. Introducing yourself by way of a gift, or meeting with an exchange of gifts, has been a tradition across human culture for millenia. Of course, if the gift is useful, it's best, but what is more fundamental is the gesture. It's saying, "Hey, welcome! I'm a friend and not a threat. To demonstrate that, I'm going to freely give you some of what I have."
So if one's neighbor brings them something they can't eat, they just thank them and decline, or ritually accept it and then quietly dispose of it.
IMO you bring food to your neighbors because you appreciate them, bringing something they can't eat defeats the purpose
It's a social ritual thing. Introducing yourself by way of a gift, or meeting with an exchange of gifts, has been a tradition across human culture for millenia. Of course, if the gift is useful, it's best, but what is more fundamental is the gesture. It's saying, "Hey, welcome! I'm a friend and not a threat. To demonstrate that, I'm going to freely give you some of what I have."
So if one's neighbor brings them something they can't eat, they just thank them and decline, or ritually accept it and then quietly dispose of it.