As others point out it's a biased comparison. Their compared Blender render ran more than 10x as many cycles as usual, ran on a GPU without raytracing acceleration which could make it slower than consumer models, and potentially it also included the startup time of the renderer.

Considering their AI achieved about 96% accuracy to the reference, it would be more interesting to see how Blender does on fitting hardware and with a matching quality setting. Or maybe even a modern game engine.