Someone with lots of land that isn’t suitable for farming is a rancher. Someone that can “round up the herd” by walking around on foot for an hour is not a rancher
FYI, “Ranchers” also send their cattle to feed lots, and during the winter feed their cattle bailed hay.
The large operations you are thinking of are mostly gone, but there never were that many Bonanza sized ones in the first place. Most were small operations. There are many smaller streams, if you will, of cattle going to the feed lots. The feed lots don’t breed them or raise them to weaning age.