@PotomacBobBecause no matter how much I like to argue with him, he's not a complete idiot?
However, I think what you're asking, versus what DS is answering, are two different things.
You're asking about whether it makes economic sense to sell what your farm produces yourself, or to the giant agri-business. In other words, if your local Kroger sources their produce and meat from farms that are within 50 miles of their store, versus selling your products to a the larger conglomerate. In milk production, for example, unless you have the equipment on hand, you're better off selling your milk to the local conglomerate because pasteurizing and otherwise making it ready for sale isn't cost effective.
In case you're curious on how big of a herd IS cost effective, Braum's in Tuttle, Oklahoma, has 15,000 dairy cows that support their own chain of 300 stores in Oklahoma, Kansas, Texas, Missouri, and Arkansas, and they will only ship within a 330 mile radius of Tuttle for freshness.
Anyway, that's also why all the farmers in the area where I grew up took their grain to the elevator and sold it that way. Much easier to sell whatever you get there, and then the elevator aggregates it and ships it out via rail for processing for whatever end product. In Lafayette, Indiana, there are two huge corn processing facilities that make corn syrup (artificial sweetener) by the rail tank car load. Now, Joe Farmer on his small farm isn't going to negotiate with them for his four truck loads of corn - Joe's going to sell it to the elevator, and let Cargill, who owns the elevator, sell it to A.E. Staley's.
That's the question I think you, PB, are asking. Hey, why are they teaching people to sell their products to the big companies, instead of themselves?
Now, what DS is ANSWERING is, if we all started small farming instead of having our big farms, then yeah, welcome to mass starvation. In 2021, the US produced 31.7% of all the corn in the world - nearly 350 million metric tons. (That's more than 6 times the entire EU.) China was second, at 16.5%, and Brazil was third, at 8.25%.
However, in soybean production, Brazil and the US are nearly equal at about 120 million tons each, while China only produces 20 million. (Note that the EU barely produces 1.5 million tons.)
As for beef, the world produced 131 billion pounds in 2022. The US produced 28.3 billion, Brazil produced 22.8 billion. (The EU actually produced 15 billion pounds, which is the same amount China produced.)
When you can drive through Kansas and see some of the giant farms running six harvesters (or more) at the same time, it's the scale of operations that come into play. We used to joke about 'poor' farmers - because while they may only have a net income of $40,000 per year, they also had $3 MILLION in equipment at their farm. I still have cousins and friends in Indiana that are farmers. What happens with small farms is they don't have the cash reserves of a big business to handle two or three bad years in a row, whereas the big agri-business can simply write off their losses. That's how they became big companies in the first place, they bought up the farmland of people that went broke.
Now, the biggest thing that would be affected by breaking up the big companies is there wouldn't be enough people to farm all the land - which would probably cut our production in half. Seriously, the way people complain about having to work even forty hours per week, you think they're going to be happy having to work around the clock at harvest and planting time? Then, of course, if we cut back to the UN definition of small farms - 2.5 acres or less - and that's not just us, that's Brazil and the EU, as well - then you may as well figure 60% of the world will die from starvation, because you simply don't have either the supply or the distribution capabilities now - or for that matter, the number of people willing to work their butts off to feed themselves, let alone someone else. (We had about 1/2 acre as a garden when I was a kid, along with 4 acres where we had three cows. 10 rows of green beans, 4 rows of corn, 4 rows of tomatoes, lots of squash, and a dozen hills of potatoes, was the normal planting. It's a fuck load of work, and backbreaking to pick beans. Some years we'd have a surplus, some years after all that work, we got squat.)