Your insistence on using the word "nobody" there is an absolute without evidence. You underestimate the visualization capabilities of savants. For my 3D game prototype, I created all of the meshes programmatically and wrote *and debugged* a mesh-slicing algorithm using only visualization in my own mind. Mostly I did indeed use primitives like spheres, cones, and boxes. Granted, huge caveats - I never finished a game from the prototype, and the meshes involved weren't that complicated; I was modeling imaginary robots not people.
It's painful for me to use GUI or CAD tools because they're so much slower and less capable than the Dall-E image generator/CAD modeler/Star Trek Holodeck I have inside my own brain. This is in some ways limiting, analogous to a mathematician refusing to learn to use a computer. Nevertheless back to your point, I'm fairly certain I could model a plausible human programmatically from geometry primitives, but I won't claim to until I try. However what I am certain of is somebody can.
It's painful for me to use GUI or CAD tools because they're so much slower and less capable than the Dall-E image generator/CAD modeler/Star Trek Holodeck I have inside my own brain. This is in some ways limiting, analogous to a mathematician refusing to learn to use a computer. Nevertheless back to your point, I'm fairly certain I could model a plausible human programmatically from geometry primitives, but I won't claim to until I try. However what I am certain of is somebody can.