What do you mean by computer graphics? If you restrict the job of a computer graphics programmer to purely a function of how many polygons can be rendered at once at 60fps, you may be right... But such a programmer would ignore information about the scene at his or her peril.

Materials: what should this object look like when it interacts with other objects? Does dirt stick, what does it look like inside if it gets cut in two, would a smooth cut even be possible, what about just trying to make a dent with a blunt object? If a flashlight is shined at the material, how does the material react?

Physics: help define how materials behave. (Indeed if we could model everything on the level of real-life quarks the need for explicitly defined materials goes away.) What's fluid supposed to look like? What about when a player character is swimming? Can we sacrifice polygon counts for distant objects, or are distant objects important in the game's physical world? What does wind do to the grass polygons? Could we use less polygons to represent quickly-moving things where the level of detail is going to be poor anyway?

Content: Does an artist need to create two copies of Tree so we can model-swap the low-poly one when appropriate? Do we need to cut content to be able to render at reasonable speeds? Do we need more content to render something worth rendering? Do we have any content to put on the screen at all?

AI: Depends if you consider procedural generation of content AI or not. Also depends if you consider a subroutine that helps optimize your graphics pipeline during runtime AI or not. Then there's the problem of many and nice animations, which you may or may not consider important to "computer graphics".