Hotdogs are an excellent example of how all the parts of an animal are used...no waste.
Much of the western world is hung up on the meat itself, a few organs like liver, with some thinking about hide/leather.
In nature, as well as earlier days and with other cultures outside ours, every part is utilized. Indeed, if you observe wild predators it's the soft organs which are consumed first long before the actual meat. Interestingly, this is also where the most nutrients are.
In the meat industry, meat is carved away, hide is processed, organs are removed, bone is ground up, fat is rendered, etc. Sausage? Traditionally packed using intestines.
Any part which is edible is used somewhere. Sometimes it's the scraps which go into things like hotdogs. Bone meal used in lots of products, including pet foods. Sometimes, because our squeamish culture "doesn't like the thought" of certain parts as food, it's shipped to other countries where it's a common food.
Regardless of who makes those favorite hotdogs we may each prefer, they're STILL an example of not wasting the lowest quality, least desirable parts of the animal.