Disincentivizing Abuse ..

The best way to 'control' flagging is for it to cost the person who wishes to use their power, to negatively impact another user. The 'cost' can be burned, in the same way that the dysfunctional Promote feature has, which supposedly has a benefit to the economy.

If you feel so strongly about something, you should be willing to put your money where your hammer is.

In Combination with the Above ..

There should be a way for individuals to voice their displeasure with posts, that only has a visual effect.