The problem with negative reps (as I see it) is that the reputation system is completely separate from the posts system. That is to say, you can give someone a negative rep for something they said, but there is no way of linking it back to an actual post the person made. So if someone comes along and rates me down for disagreeing with me in a single post, it is essentially a mark against me as a person, rather than one particular opinion I had espoused.
As Synackaon said, the member "In This Mind" decided that pretty much all men here were rapists after some of us suggested that women can do things to reduce the risk of rape. Any sane person in that thread who read our comments could see we weren't trying to victim blame, but were instead saying that there are situations that increase the likelihood of rape (as there are with pretty much any crime). However, a visitor to our reputation profiles would only see the negative comment, and not the context.
As Synackaon said, the member "In This Mind" decided that pretty much all men here were rapists after some of us suggested that women can do things to reduce the risk of rape. Any sane person in that thread who read our comments could see we weren't trying to victim blame, but were instead saying that there are situations that increase the likelihood of rape (as there are with pretty much any crime). However, a visitor to our reputation profiles would only see the negative comment, and not the context.