I don't know about incompetent. But the way the structure was setup it seems most of the 457 visa coming in are the white collar/professionals that are not really needed considering how many professionals are out of work.
IT workers, in particularly have seen no wage growth because of the abuse of the 457 visa system.
Other professionals have also have found it tough because of the lax visa rules when it comes to students on completion of their course.
The Rok I don't know if your incompetent but do you earn as much now as someone that is a citizen and when you came on a 457 did you earn less then someone with the same experience as you who could have done the same job you got?
I know from a number of sources that various visa schemes have been abused by employers over the last decade in many industries, with many that don't really have a real shortage of qualified workers.