I could be off the mark here but I'm fairly sure the world isn't ray traced. Ray tracing involves projecting light from the "eye" towards the scene, whereas in real life the light is being projected from the scene towards the eye.
By the way I was able to read the article. One thing I'd like to point out is that ray tracing lends itself better to parallelization because you can calculate each pixel's color independently of the others. That could be a major plus in the future that helps it win over scanline rendering.
By the way I was able to read the article. One thing I'd like to point out is that ray tracing lends itself better to parallelization because you can calculate each pixel's color independently of the others. That could be a major plus in the future that helps it win over scanline rendering.