Yeeessss but the prices people are getting for the commercial sheep from the buyers eg abbatoirs/processors make up for the increased costs of rearing them, unlike with pigs! And altho you cant feed chickens scraps, they do eat the grass/plants/insects in their surroundings and dont take much feeding.
I do agree that a weaner is still a very very good proposition in terms of a comparison with butchers pork, its just that most people dont look at what they would pay for that much meat as they buy it bit by bit if they buy it from shops. Plus unless you have the fencing/arc etc to keep pigs there is a big one off expense.
Dont get me wrong, at the moment the buyers of weaners are getting a VERY good deal; its the breeders who are hurting like mad. But if you have the land to make your own hay, and choose low input sheep breeds, who basically only get grass and hay, then that is what many people will do esp when they look at the sky high price of lamb in the shops.