Reviewers have the power to block the publishing of papers they are reviewing if their suggestions to cite their own work or that of their network is not complied with, see: https://www.elsevier.com/about/press-releases/science-and-technology/elsevier-works-with-wageningen-university-to-detect-and-prevent-citation-manipulation. In which cases should citation pushing be tolerated or is it morally not allowed at all? Were you involved in citation pushing yourself as reviewer or as the author of a paper?