Says who? Mine digest it all right, though they don't eat pure fat, but they eat fried bacon and leaner pork parts. They don't eat pure fat not just from pork but from fish and any meat. They just leave it on a plate.
i guess they cannot eat if you don't give it to them. My cats eat human food and cat food when I do not have meat or fish that I can share with them. They can eat meatballs, chili(they leave beans out ), chicken, chicken soup with dry cat food in it but I am not going to give them chicken breast or a steak or a salmon - t oo expensive for my budget. I feed them pork and beef and do not see the difference.