Those skills are a lost art. My grandpa could do the same thing with a rabbit, using every part from the ears down to the feet for stock. It's about knowing the animal's shape, not just cutting. That guy probably saved you a ton of money on meat too, buying whole is way cheaper.
Yeah the "knowing the shape" part is so true. It's like a different kind of respect for the animal, not just getting the meat. My uncle was like that with deer.
Oh totally, my grandpa was exactly the same way with hogs. He'd break down a whole pig and know exactly where every cut came from. Saved us a ton on groceries too, buying whole was way cheaper than the packaged stuff at the store.