Depends what you mean by memes. The things on this site aren't really memes in the original sense of the word. The reason these things are boring is probably that as humor they fall on the far billboard end of the billboard-Shakespeare continuum: they are designed for quick (but inevitably shallow) appeal.
It's just a figure of speech. There are plenty of other figures of speech that would be even more "offensive" if we applied this unreasonably strict standard to them.