I emphasize poorly because law review placement is one of those strange things. A great many of us say law review placement is not important and then act completely differently. Maybe SSRN citation only is a way out of this inconsistency. Plus, the SSRN-citation-only idea is a great way of removing, largely 24 or 25 year old, students from the law school and law professor ranking process. Put differently, maybe very differently, isn't a system of no referees better than the current system of student referees? SSRN provides that opportunity.
Even if the schools listing only SSRN cites are doing it just to drive up downloads (the importance of which I think is massively overstated), it seems to me that it is a trend others might consider following.