I can only say wow, you were right. They only DVNR'ed the luma.
Yeah, I did quite a bit of experimenting for my now-defunct SWOLT project. Isn't it weird?
Most defects (e.g., dirt and dust) exist in luma, so this probably made sense in the early '90s as a way to reduce the required time for processing.
It would take some insanely intelligent plugin to see the difference.
Agreed, but what do high-end video cameras use? They seem to be quite intelligent...