Why do feel the need to argue with them? They told you what they thought, so what? But if you knew, you would "clear that up" (there's the arguing and/or retaliation) and only end up pissing both of you off. Take it with a grain of salt and move on.
And again, while using the report post function can be good in many situations, it puts a huge burden on the staff to monitor everything, something they can't do. It does not need to be used in all cases. So someone told you they disagreed and left you some neg rep, so what? You were not doing anything wrong so there was no need to report you and that person did not feel like getting into the thread, they left you their opinion, so what? Is that so bad?
As a side note, maybe if you quit complaining and arguing about the system, the staff has already weighed in, you wouldn't get bad rep. We've wasted 3 pages and I've gotten LOTS of positive rep, how about you? If the system on these forums bugs you so much, there are other forums you can go to.