All users initially do carry the same weight. You don't gain "weight" at some ridiculous rate.
All moderators approve/disapprove flags, if someone is trying to abuse the system, if they flagged something that doesn't fall under the categories, if they're being overzealous in their flagging, these can all be considered incorrectly flagging a post. The difference is that they are all looked at individually, this way we can look at the post(s) and make a decision based on the specifics. We can dismiss flags to prevent any weight deduction, which is primarily what we do in cases of false-flags.