Zombie gave you a pretty good indication, the main point of focus when they'd use something like this is a quick turnaround. They'd want to maximize profit over a short period of time, before you have time to react and then disappear, with the only trace left being your details.
The real trick to fake identities is the harvested ones, there are extremely hard to pull off but worth millions when done correctly. They are essentially exactly the same situation as someone stealing your identity, only, there is no person on the other side of things. You could literally assume the identity without anyone ever questioning it.