You can imagine "1 + 1 = 2" not as an important question in this context, but rather a proof of concept for the system they devised. It's a bit like the story about a "black triangle" [0]: a rather useless model passed through a rendering pipeline to produce a result any OpenGL novice can scramble in a couple dozen lines, but showing that the whole pipeline does, indeed, actually work as intended.

[0] https://rampantgames.com/blog/?p=7745