I've read that too. James Fallows has an interesting piece about these and other workers who populate the factory-dormitory world in China. A lot of us assume they're being exploited, but Fallows argues that they're more entrepreneurial than that. They can save enough money in a few years to go back home and buy land, something which wouldn't have been possible before. It would be interesting to know how many actually do this.
On the one hand, it's great people who need the money have this as an option.
On the other hand, the system owners could undercut any price by selling resources created by fiat, with a few keystrokes. So in a sense, all this activity is burning away hours -- human potential -- in an inefficient process someone else could do effortlessly. And, the whole market exists only as long as the system owners won't deign to offer such services directly.
So I can't quite decide if the whole phenomenon is encouraging or discouraging.
Or half as big. The article and study aren't convincing.