[mahdi7d1]

Each screen is off in some way but not the same way. By grading on a screen that is properly color graded you prevent the picture from looking trash on some. Imagine color being off is a vector in 2D space starting from origin. It can be in any direction. If your monitor is off too then your color error vector would be added to the consumer's color error vector. It might make the color even better for some when those two vectors cancel each other but make it outright unbearable for other's. That's my understanding of it and not very accurate.