I may be a bit naive. However, it sounds to me as though this could be a tactic that is designed to "intimidate" applicants into ranking them higher. I do know that according to FREIDA, MGH gives about 90 interviews for 10ish Psych. positions. If they -- MGH -- feel that it's necessary to interview 90 or more applicants, then I have to believe that other programs have to be a tad cautious/zealous with their tactics!
BTW, even stellar programs can go unfilled. A couple of years ago Duke failed to fill their Psych. positions through the match; yet, as a rule, I would imagine that they "assume" that they will not have to go "too deep" into their rank order list!
Not sure if this helps; but, I thought it might!???