Just trying to understand this...
So for example, a usual, basic setup for shooting a wrist watch that has the main light source creating a direct specular reflection on the glass that's covering the face of the watch would require a "gobo" to block the reflection on the glass, while the rest of the object and/or tabletop is usually lit in one way or another.
With your projection technique, you could project white (from Photoshop) onto a giant translucent scrim and then SUBTRACT by painting with black wherever you want, and/or project black and ADD light precisely wherever you want by painting with white?