Unity Global Illumination + Ambient Occlusion + Dynamic shadows

I'm trying to figure out if there is a way to have any sort of baked ambient occlusion while at the same time be able to move the light around in the game at runtime.

When I set my light baking to Mixed and I bake and I play the game and I rotate the light, it's pretty much as if nothing at all is dynamic (ambient GI is set to Realtime). The shadows don't change, but at least I have AO. If I set the light to Realtime, there's no AO.

Don't artists bake AO in meshes even before they import the models and textures into Unity? Why can't Unity bake some sort of AO with realtime illumination?