I think in principle it's a good idea. It's been addressed before by others including Alan Ross who wrote a series of four articles on masking which were published in View Camera.

If the mask were in placed in contact with the print, however, hard edges would result. Instead it is placed just above the negative. I've not tried the computer generated masks, but have made simple masks by drawing on the acetate sheet with a pencil. It does make tedious dodging very much more manageable.