[mindslight]

It doesn't. It's called the "analog hole" and has caused much head shaking with regards to the media cartels' attempts at digital restrictions management on the output side.

Trying to secure that regime on the input side would seem to be even more fraught with problems. At least using the analog hole for the output side causes quality degradation from reencoding the content (the most common goal is digital redistribution). Whereas on the input side, the content begins in the digital domain so it's not even adding an extra analog step.