i know where ur going with this bro... but its not necessarily true... there are heaps of powerlifters with small looking backs... sure, they can pull insane amounts... but that doesnt mean theyve got maximum size...
i agree that one needs to up the poundage progressively in order to get stronger & bigger, but i dont see any correlation between poundage and size...
take the ANIMAL back vid for example, Wraths hammering away 405 for high reps&sets & his back is wide & thick..