Members of organizations such as the RIAA and MPAA hope to prevent the creation of any copy of digital media -- even those which consumers are legally entitled to make under the doctrine of "fair use" -- by encrypting audio and video until the very instant they reach your speakers and screen.
Surely it wouldnt be long before someone just plugged a cable from their line out strait into the line in, I mean they cant stop you sharing your home recorded stuff can they?