Prior to 1980, the federal guidelines were in place to ensure no company became a de facto monopoly. This was changed to encourage efficiencies with the expectation that cost savings would benefit consumers. This has been shown to have failed and a return to the monopolistic concentration of control of markets has instead been allowed. By changing the guidelines of enforcement back this can be reversed, benefitting small business, small farmers, and the American consumer.
For detailed history and explanation please refer to this article in Salon magazine:
http://www.salon.com/2014/06/29/free_markets_killed_capitalism_ayn_rand_...