It seems like their basic framework (ironically) could be extended to include other things, like incentives (eg for apparent production of "ideas").
One thing about these models is that they don't necessarily get into why things start to be imitated. It seems like the ability to imitate would be related to the spread of the ideas? That is, even if there's a valid idea if the imitators can't or won't imitate it, it won't be imitated. I guess it speaks to whether ideas have value outside of the social milleu they are presented in at a particular point in time. This might seem self evident, but then you have to think about the diffusion dynamics being a property of ideas vs imitators. The authors discuss this in terms of experts not being able to produce novel ideas fast enough, but how would your distinguish that from imitators not understanding how to imitate novel ideas?