[cubefox]

Modern optimized path tracers in games (probably not Blender) also use rasterization for primary visibility, which is O(n_triangles), but is somehow even faster than doing pure path tracing. I guess because is reduces the number of samples required to resolve high frequency texture details. Global illumination by itself tends to produce very soft (low frequency) shadows and highlights, so not a lot of samples are required in theory, when the denoiser can avoid artifacts at low sample counts.

But yeah, no way RenderFormer in its current state can compete with modern ray tracing algorithms. Though the machine learning approach to rendering is still in its infancy.