I've seen it, and done it myself. I did not care for it though, because the length of the bar didn't make balance the easiest thing, nor was the positioning on the bench. I found I either had to spin around reverse of a normal bench press or be hanging so far off the bench it just felt-and looked-silly.
Some guys, the one I first saw do it, do not have heavy enough pre-made BB's to use. If they can use 150+lbs on Skullcrushers, the heaviest I've seen at any of the gyms I've seen is 110#. So, for them, it makes sense.
I still don't advocate it though.