You are right but a large flag that is without hate (unless used to counter spam) should not get close to 0$.

@haejin post may not be worth 300$ to some people but they're clearly worth more than 1$ for a few people.

Flags that takes away most or all of the reward should be accompanied with an explanation, and here is mine.

To be able to see the result of a flag you can use the Steemit MoreInfo addon for chrome/firefox