Not a direct answer to your question, but I believe there are still A/V shops that use Amiga Hardware.
Perhaps a few TV news outlets are still using it since the turnaround there is so tight that everything needs to be "just so" to meet your deadlines, but even then, I have difficulty believing with the move to digital and HD that you could even get your footage onto an Amiga and work with it. I can't believe the hardware could handle HD.
Regardless, your point is probably valid, but I have to imagine there is at least a handful of A/V enthusiasts taht swear by the RGB based computers.