Comment by kelnos

I think you're misunderstanding. No one is saying that a GPU isn't involved at all.

But if you rasterize your frames into a buffer using the CPU (and not OpenGL, Vulkan, Metal, D3D, etc.), and then scan that out on the GPU, that is indeed software rendering in the sense that matters here.

The idea that software rendering is impossible because the GPU owns the scanout buffers is just silly pedantry.