Comment I have never seen this (Score 1) 107
I am an author and an editor of a journal that could use a higher impact factor to get noticed. But I have never been "encouraged" to add a reference that was not clearly missing (there have been one or two of those, due to inadequate research on my part), and as an editor I have never asked for additional references except in cases where there was clearly prior work that the authors should have been aware of and should have cited, usually because the missing references actually showed the results the authors were claiming as new contributions.
So I think this is a case of extreme self-selection, and perhaps a particular field or journal where some practices need to be examined. I just don't see it in Computer Science, Economics, or related fields where I read and publish.