There are ways to diminish the possibility of abuse of the system, I would think. Increase the reputation user spread setting. Limit the amount users can give daily. Make everyone's rep power the same, so there isn't a small group of people with max rep power circle-jerking each other or who can make or break someone's rep in a short period. Etc.

Obviously it wouldn't be perfect. What is? I don't really care if it's perfect or not. The only reason I mentioned it is because it seems like a way to incentivize people to act civilly. I think it would have that effect to some degree regardless of whether or not it is flawed.