I don't think I'm the right person to do it (because I get really angry about the issue). It would be good to have someone who can explain it to them calmly, why it's wrong to complain about other people's memes on a meme site, but without getting too worked up about it.
But even if I were the right person to do it, it may not be an achievable goal anyway, to stop people whining about reports. It may be more sensible for us to just resign ourselves to the fact that as long as there are meme sites, there are always going to be repost whiners there.
Just like I guess they have to get used to the fact, that as long as there are meme sites, there are always going to be reports there (no matter how much they complain about it). 😉