You can zoom to higher magnification for working on fine detail. Easier to fix, adjust, and change things. Media gets cheaper as the technology gets cheaper. Media evolves to remove limitations. Media can be made to violate physical laws that bind real media.
Media can exhibit idealized behavior.
Perfect masking and friskets. Doesn't deteriorate, warp, fade, crack, peel, discolor or turn yellow. Can be transferred easily to another place. Can be scaled and resized. Can be viewed and distributed by computer without first having to be digitized.