Any component could utilize that digital optical port, not just DVD players. It's labeled that way since it's a popular type of input component that users happen to want to connect.
Please review my posts earlier in this thread. Bottom line is, you only need the digital optical cable from HDTV back to Pioneer receiver in order to enjoy audio output from the various SmartTV apps. Otherwise, no, you wouldn't need it., especially since you do not use the built in HDTV tuner, but have a Comcast cable box.
Also, see if you can eliminate either the HDMI cable or RGB component cable between the Blu Ray player and the HDTV. You don't need both, but one will most certainly work.