As the big 4 took control of the meat market, they threw around their weight to squeeze farmers for better and better margins. Then they started to consolidate vertically and out-right bought out many of these farmers. Commodity operations lost their ability to negotiate prices and had to adapt or die... this is how CAFO farms started to become the norm.
CAFO stands for concentrated animal feeding operation... and they have been around since the 1930s. These are massive farms where cattle is confined to gain weight for 45 days in a year. CAFO farms have allowed BETTER and CHEAPER meat to become the norm, they have driven prices to the ground. They are the reason the price of meat, milk and eggs can be so low (hello Walmart, Wild Forks, etc..)
This is how a CAFO farm looks.
However, not all is good about CAFO farms. While the average quality of meat increased, high end meat became scarce. Moreover, meat became more unhealthy as a result of the processes these farms would use. The average weight of an animal went from 700lbs in the 1980s/1990s to over, 1450 lbs in the late 2000s. Everything became about price and profit, and the art of fine meat started to disappear. Last but not least, as CAFO farms rose to prominence, small independent farmers started to disappear as they could not make ends meet.