There is hard evidence that academics and journals are manipulating citations to (unfairly) improve their reputation. There is a summary of this and a call for more evidence in the post "What do we know about journal citation cartels? A call for information" at https://www.cwts.nl/blog?article=n-q2w2b4
However, these deliberately fraudulent cases are simply the extreme end of a spectrum of practices which need examination, understanding and (of course) simulation modelling. It is well known that many referees demand that papers cite certain papers (e.g. their own) as a condition of publication. It is well known that in some fields, there is a strong social norm that one should spend the first 2-5 slides of any presentation citing previous work (whether relevant or not). This demand that outsiders should learn the 'key' references before being allowed to present their research has advantages in terms of not repeating past debates/research and to aid the coherence of the field, but it is also an effective means of excluding outsiders and ensuring insiders are well cited.
There have now been a stream of simulations that touch on the processes of peer review, but a wider set of simulations and analysis of science are needed that focus upon the tendencies of fields to become inward-looking to the extent that some look more like cartels than academic discussions.