If you find
There is an unfilled demand for fruits or vegetables in your region
You have enough labor and skills to operate this way
Other enterprises are not providing sufficient income
A market garden can be the major enterprise on the farm and can generate significant income.
Or it can just provide sufficient income to keep things rolling financially until another enterprise comes on line. I first came across this approach when I was a boy and my Uncle Bill was growing rockmelons between the rows of young peach trees to make some income from the land in the 5-7 years it would take for the peaches to become productive and to build fertility.