The central thesis of "economies of scale" is once the fixed costs are taken care of, it's more profitable to build something at higher volume. This implies even if your product isn't the best quality at the start, or takes a long time to produce, even if it is a little bit profitable, you'll have the income necessary to make the product better. Essentially, the more you can sell your product, the more you can actually invest in making the product better.
In conventional agriculture, start with a product like Tomato. You can only sell lots of Tomato if you can make lots of Tomato. The only way is if you have lots of land, which requires either lots of feet or lots of machinery to plant, weed, fertilize, water, and harvest. So, add a tractor, a processing factory, synthetic fertilizers and more to sell Tomato at high volume. Conventional agriculture has grown to feed over 65% of our country.
According to the world bank, conventional agriculture also accounts for 70 - 90 percent of increases in food production, which means all the food abundance we have comes directly from big ag. Without a surplus of food (meaning you make more food than you can eat yourself), we wouldn't have cities, writing, philosphy, art, robotics, computers, and more. This follows from the fact cities were created from division of space and labor: we intensified farming practices so we could grow more food on less land with less people and send people to highly concentrated towns/cities.
Obviously, conventional agriculture is pivotal to us being here and they benefit largely economies of scale.
However, the major inputs to agriculture actually are deeconomies of scale. Tractors, synthetic inputs, pesticides, etc. all lead to an increase in average costs the more the business scales. The more pesticides you apply, the more pests become resistant to disease and even more is needed to kill the same amount. The more fertilizer is applied without considering the yearly fertility of the soil, the more the intrinsic fertility goes down and the more fertilizer is needed the next year.
Many farmers have realized that you cant grow the same crop on the same piece of land with the ideals of economies at scale for over 100 years without diminishing returns. After a certain point, the amount you need to spend on fertilizer, disease management, water increases faster than the price of the product. Increased volume of production in the economy of scale actually led to lower profits.
When corporate farms deplete the fertility of their soil or suffer from prolonged drought, they move to another place and start again. The result is major farm consolidation: the conventional farmers benefit from high profits for the first 100 years and since they have the money to buy more land, they continue absorbing more farms and generating revenue, leaving deserted farmland in its tracks.
doing this across America, Latin America, Africa, India and more means you have plowed, then deserted all the land in the world. At times, you have made insane quanities of food. Now, once you've run out of physical space, what next? Shipping fertile soil from mars? food shortages around the world?