This thread is entertaining, but unfortunately as Rawalanche correctly pointed out, AO is being misunderstood on a conceptual level.
GI is a more accurate lighting model that makes AO unnecessary in your lighting stage. GI encompasses far more of light’s actual behavior as rays travel through a scene than AO can ever be made to represent.
The comments about whether studios use AO or not… that’s kind of a moot point. But yes, big studios use AO. They use it for compositing and in shaders and material development yes, like both Rawalanche and mentioned. (Not contradictory points, by the way)
Big studios who have raytracers would be foolish to use AO in any way in their base light transport and rendering model, and they don’t. But they do use it in grading, comp, shader dev, etc… for dirt and wear masks etc…
The GIF mentioned before does in fact make it clear that GI is a better and more realistic look. The SSAO shows artifacts and unnatural shadowing in comparison. Why would you want it?