The thing which that article leaves unsaid is that this lifestyle existed in the context of seasonal migrant workers (hobos) who were still necessary to the not-yet fully mechanized agriculture of the time.
One work which touches on this is Louis L'Amour's autobiography: _Education of a Wandering Man_ which is a great read.
There's still a lot of non mechanized agriculture in the US. Fruits especially are often hand picked. Strawberries in particular can be pretty grueling [0] because they're low to the ground. Even the semi mechanized version has the workers lying on their bellies rapidly picking as the tractor tows their platform along. [1]
Yes, but there aren't masses of people moving in a seasonal migration following the work as there were before the development of the hay rake, combine, &c.
There are fewer but there's still a lot of itinerant workers that follow the harvests. There's not work year round in one place for fruit pickers but there are several harvests each year they follow.
One work which touches on this is Louis L'Amour's autobiography: _Education of a Wandering Man_ which is a great read.