I don't recommend that people get their information on cultural evolution or memetics from these folk - or this book. They don't know what they are talking about. Their chapter is a hatchet job on memetics - and a highly hostile account on cultural evolution. If many people are confused about cultural evolution, this sort of material is a good example of why.
The whole thing is so transparently a straw man attack that I can't imagine that many will be taken in by the contents. Maybe Elizabeth and Tim really do think that meme advocates are stupid. However, by doing so, I think they just make themselves look stupid. Step one for a critic is to try and find a sympathetic understanding of the material they are criticizing. The value of their efforts often depends heavily on how well they perform this step. Elizabeth and Tim have failed at this stage: they don't understand the material they are criticizing. The results are hopeless. It seems like a matter of embarrassment for the editors how this kind of material made it through the review process.