Double Arm Backstroke Drill?

Can anyone tell me a positive reason for doing a double arm backstroke drill? The only thing it seems to be good at for me is hurting my shoulders, so I refuse to do it. When I think about it, I can't come up with any reason why this drill would do you any good anyway. In real backstroke, you are supposed to roll your body from side to side, right? That's a key part of the stroke. When doing a double arm recovery, you can't roll at all. So what is the point? Whenever a coach assigns this, I just quietly do something else. If they were to try to "encourage" me to do it anyway, I'd tell them what they could do with that idea.