That is streaming though, whether it's via Wi-Fi, Ethernet network or optical cable, it's all digital. You're passing digital audio data to the Denon to convert into analogue signal, then actual sound.
It's just a case of which is more convenient for you to use. If the Denon is next to the PC, then you might as well just use optical. Wi-Fi or Ethernet to your network makes sense if the distance is much more and optical is less feasible.