Downvoting a comment and downvoting a meme are two different things.
If 2 more people downvote a comment than those who upvote it, it becomes a Low rated comment. It can still be seen.
If 2 more people downvote a meme than those who upvote it, it gets pushed back into submitted status. There is no chance of it being seen again by anyone unless you link it in a comment that others see.
That's why I'll downvote a douchey comment, but a meme has to be SUPERDOUCHEY for it to get a downvote from me. I just ignored anti-Trump memes.