The DMCA is a bit overly broad to be considered just a copyright law. For example, just breaking encryption on a DVD is technically illegal regardless of whether you then go on to do something otherwise illegal (make and sell bootlegs) or perfectly legal (make a space-shifted backup copy on your hard drive).

IIRC this was an intentional handout to media companies who were angry that ripping CDs is perfectly legal. They had to find a way to make doing the same with DVDs illegal.