In some cases that can be true, but with the current shotgun approach to academic publishing, the authors have often republished variations on a paper, covering slightly different aspects with different framing, in 3 or 4 different venues, so sometimes there'd be scope to choose to cite a non-Elsevier one.
Ok. This means that even more authors might republish the same research in different venues - just in order to avoid their research being ignored because of their choice of journal. Seems like another danger of an Elsevier boycot to me.
