A lot of places do sell stock. Particularly the high-end places that do a good business in prepared foods, usually have some semi-prepared stuff like broths that are good. But I have seen it in a Kroger’s as well.
Where I used to live I would buy chicken stock from the Chinese restaurant down the block. They cut up several dozen chickens a day and had much more stock than they could use.
My supermarket doesn’t sell ground chicken, but they have home-made chicken sausage. I bet that’s where the scraps go. Although, I suppose they would still have bones they could make both from. You know, I bet the prepared food area has soups, although I’ve never noticed.
I add broth to dishes like chicken with ginger and scallion, where I don’t think a pronounced vegetable flavor would be helpful. But for a lot of dishes, sure. For my bean soup it would likely be nice.