Actually, my Dad grew up on a mountain where, every day after school, he would come home and gather up the pig and cows that had been let free to eat for the day. So there's certainly use cases for letting a pig roam free and gather some forage. By the time I was growing up we had chickens, which had to be brought in at night to prevent predators from eating them, but otherwise could roam the yard to eat worms and the like.
Also a horse that kept the grass in the yard short without us having to mow it. There were goats, but they weren't allowed free mostly because they went and ate mountain laurel and poisoned themselves.
It's kind of strange to take a working animal like a cat, bred for pest control, and stick in a little indoor room and never let them out. Did farmers originally lock up their barn cats in the barns? I don't think so. It's actually a problem when they accidentally get locked up in a shed or a car or something, because they aren't out doing their jobs.
Seems nuts to me that the author belittles letting them outside.