The problem is in the solution. Rationally, those Herdsmen need to hash out an agreementfor the fair use of that land to keep it just below it's carrying capacity.
But what really happens that some 'nobleman' declares the entire commons to belong to him and sends a goon squad to wipe out any herdsman who disagrees. He then 'allows' the herdsmen to use the land in exchange for a painfully large share of their productivity. For some reason he expects gratitude for that arrangement.
Alas, we've moved beyond even that. Now the 'nobleman', seeing that the herdsmen are making do with a smaller commons over the hill but unable to grab control of it sends his goons to salt the earth overnight so the herdsmen will have to 'rent' land from him.
But even that isn't enough for some. They want more 'rent' than any herdsman can pay while still making a living. So they leave the field fallow while trying to grab even more land. For some reason they think they can squeeze blood from a turnip.
If you find that unbelievable as an analogy, explain why there are entire blocks in NYC that haven't seen any space rented in over 10 years, yet the asking price hasn't budged even as the neighborhood has been given over to rats and junkies.