Source?
This is not the reason I'm aware of. I believe it's all about price control on the supply side, not capacity. Just look at that old SCOTUS ruling that forbid individuals from growing more more a specific amount a wheat. They used the interstate commerce clause to say that the secondary affects of growing your own wheat jeopardizes the wheat industry due to the inability to control prices.
For example, there are current talks about a food crisis due to the war in Ukraine. Yet the USDA has not authorized the land enrolled in conservation programs to be utilized. Also, that land tends to be the lower producing land. Farmers get paid the same for the enrolled land, so they enroll the lower producing acres.