It was an online poll which drew in 4300 Nature readers, and the proportion claiming such influence was higher than in previous surveys.
The difference could be down to the Nature poll’s limitations: respondents were self-selecting and people who have been affected or are interested in coercive citation may be more likely to respond. Whether citations are ‘superfluous’ is likely to be subjective in some cases, and respondents were not asked whether reviewers were asking for their own studies to be cited.Dalmeet Singh Chawla, “Two-thirds of researchers report ‘pressure to cite’ in Nature poll” at Nature
That said, as time goes on, the gravy train gets longer and longer. Lots of rackets collapse when there are just too many users to pay off.
See also: Peer review and citation ring busted