I think DPC is a victim of the Boba Fett syndrome, where what was intended to be a minor support/antagonist character blows up in the minds of fans so he has to provide additional content to satisfy that group. It's a testament to his ability to write compelling back stories and story-based actions for disparate characters who appeal to a wider audience than he originally intended. You now have fans of Quinn/Rio/Nicole/etc. who will be disappointed (and rather noisy) if the story doesn't provide them some sort of alternate path with MC instead of sticking with the original plotlines for the 5 MGs as originally planned. This sort of scope creep is a killer for development if it's not kept under control.
Yeah, etc. is right because I personally would make arguments for Jade, Camilla and Lily too, and now Nora is floating around where narratively if she's becoming a thing it's not just to be someone to sleep with because she usually doesn't do repeat hookups based on current writing.
Doesn't help either that DPC kind of set that up expectation wise with the MC's visions of his lovers on the non-main girl option at the forking decision at the end of Episode 8. Kind of implied the range of ending choices expanded beyond the original main LIs.
Edit: Replaying Episode 9, the texting sequence on the "Other" path includes Nora, Quinn, Jade, Nicole, Lily and Rio (with Cammy included w/ Rio so two birds one stone). I think that's your expanded LI roster.