I know nothing about farming, but I do know something about manufacturing, and your arguments seem as applicable to that area.

Having a single centralized point of control will always lead to better short term results due to economies of scale. These advantages then trickle down to both labor and the consumer.

The problem, in economic terms, is a variation of the agency problem. Once control is vested in just a few hands, there's little incentive to follow regulations or to hold prices down. What follows is a slow process of erosion. After the buyouts and predation, the few remaining principals will ultimately come to the realization that collusion is more profitable than competition.

That's what fuels this debate - people on either side of the argument can always find statistics to prove the efficacy of their stance by simply positioning the horizon of their study to their benefit. Furthermore, the advocates of trickle down can monitor public opinion, use payoffs and propaganda and even modify their behavior just enough to avoid regulation.