Those audio cables have in fact been obsolete for many years now. It's been a long time since I have seen one in use.
Go to each of your CD and DVD drives in device manager. Right click on them, and under the properties tab, check the option for enabling digital audio.
Voila! No more audio cables needed.
There are undoubtedly a whole lot of people using the cables when they don't need to. Worse yet, there are probably lots of people with both D/A turned on, and the cables plugged in, so the cables are there but doing nada.