Not exactly, it’s more like because the cherished agricultural industry would disappear.
Here’s the assumption. Farmer’s cost of production for a bushel of corn is $2. Open market price for corn is $1.95. But the “loan” (or subsidy) price for corn is $2.15. The farmer sells two bushels of corn and forfeits one bushel to the loan program, thereby getting $6.05 for corn that cost $6 to produce.
Take away the subsidy program. Farmer goes broke and a) sells to megafarmcorp which may be able to grow corn for $1.94, b) sells to a land speculator, removing that land from production permanently or c) goes bankrupt, leaving the land to the bank, which may not find either a land speculator or a megafarmcorp willing to buy land in that area.
One important thing to remember is that land to a farmer is an asset that must be used. A cattle rancher or dairy farmer can, within limits, expand or reduce the herd to match market demand. But land is a fixed expense, whether it’s used for a crop that year or not.
The other thing to remember is that if production stops, the infrastructure in that area also stops. The grain elevators and feed mills close. The infrastructure is harder to rebuild than just taking land out of production.
A real life example of this happened in the mid 1970s. Congress allowed the sugar subsidy (it was also a program to limit imports) to expire. Three things happened:
Foreign governments dumped their own subsidized sugar into the U.S., causing prices to plummet.
Domestic sugar producers, particuarly in the north-central states, went bankrupt, and the mills and related industries went bankrupt along with them.
The price of sugar then skyrocketed as other producers took advantage of the decline in domestic production to raise prices.
All of this may be brutally efficient from a free-market standpoint, but remember one other variable. In the U.S. and most other countries, some inefficiency in food production is valued, in case of drought, blight or an interruption of foreign imports. (The last rationale is particularly evident in Europe.)