To make yellow, you need to combine green and red. When you overprint green on top of red, you find that all color is blocked. The green layer blocks its complement magenta which includes red. There is no color left to be reflected from the paper. Additive colors cannot be used because they block two of the primary additive colors.
Subtractive colors block only one.
This is why layers of cyan, magenta and yellow are used in many color systems, including photography and printing.