For as long as institutions keep focusing on the number of papers published by researchers in order to promote the latter, researchers have every incentive to publish as much as they can. Also, the fact that publishers have a vested interest to publish (they get money from those who want to be published) does not help. Anyway, I remember reviewing a paper which was very little more than a rehash of one of the authors' previous papers setting N = 5 . Never mind what N was. I rejected it, but I wonder whether they still got it published somewhere else, after paying.