To be honest, I always wondered about this myself. Maybe some copyright/legalese stuff there.
In a way, I like it, but for a completely different reason. Let's say I'm running an lp signal into the 950, but recording it back out through the tape outputs. (I'd rather use the A-to-D converters in my DAT deck for example.) Because we know the 950 doesn't output anything through the digital rec outputs, we can be reasonably certain the 950 isn't throwing in an extra (and unwanted!
) A-to-D and D-to-A conversion before the signal gets to the tape outs.