Flagging CAN be an abuse of power. But just as its everyones right to upvote what they want, anyone can downvote what they want. And if someone doesn't like a meme you post, its within their right to downvote. But just like in the real world, actions have consequences, so if enough people think a flag is abusive, their reputation will come under scrutiny.

I'm guessing there is history between you and @dantheman, hence your foreknowledge of a downvote from posting something like you did. Knowing something will be received negatively and doing it anyway without any real value added (and from the way you describe it, that post would be a non-value-added).