the demand for wings, skinless boneless breasts, etc is so great both in groceries and restaurants, that there is a lot of the chicken left over...backs necks feet, skin, carcass etc...all of which can be simmered for stock and broth. The demand for commercial stocks etc is a good thing in helping the food industry waste very little.
You can make stock at home from leftovers. Buy whole chicken and roast, making stock from the carcass after a meal or two from the bird. Cut your own chicken parts and make stock from the trimmings and carcass not used. etc.
Nothing in my kitchen goes to waste.