Back hyperextension - Silly question

I propably already know the answer, I just want to make sure and maybe get some new ideas, etc.

But the thing is... I train my back on a roman chair, with a plate. The plate is pretty heave for my hands as I rarely do any isolating training on my biceps and so I keep the plate with my hands, close to my chest while I train. But I see some who lift the plate on their back and train so.

So the question is, is there any benefit on doing the latter? My back is quite strong unlike my hands, so putting the plate on my back doesn't feel safe or would make me train with smaller weights than what I'm able to.

I understand that you need to keep the plate real close to your body and that you need to do the lift on your back and not on your hands and no cheating any way so I guess the answer is that the plate's place is irrelevant?