Cheese producer buys milk from farm X to make cheese. Grocery store also buys bagged milk from farm X. Cheese producer makes low quality cheese. How will that lead to people buying less bagged milk?

I said this in another branch of this thread, but I'll repeat it here. You can make the argument that low quality milk from farm X leads to people buying less milk, but I don't see how low quality cheese can cause people to buy less milk.