The problem with systems like this is that your success rate is based on quantity of data, and not quality. The more data you have on a candidate, the more likely that candidate will move forward. This shifts the focus from knowing the job, to polishing your profile.

Simply put, your "performance gauge" as a programmer is directly correlated to your knowledge and expertise, NOT to how well you are at updating your profile and recommendations.

To me this is primary problem of hiring websites at the moment. It creates a sort of game that you can then get better at (but which I don't care for, and unfortunately creating a disadvantage for myself).