Floop78 has some good points.
If certain restrictions were put in place it would work like the system should.
Of course, any mention of rep in posts would be against the rules since it's meant to be a natural like system, and not a fishing pond.

Also, what would you think about having rep enabled in only certain areas of the forum where it would be good.
For example, no rep in discussion because as others have said, if someone disagrees with you they'll just -rep you.
But there could be rep in the market so that users can see easily whom they can trust and who is deemed by their peers to be better.