Maybe you should go tell that to ILM, Weta, Pixar, Disney and a numerous other high end Visual effects and CG cinematics companies, perhaps you should go tell them you are doing it all wrong. to this day :).
It is clearly wrong on every level to say that you no longer require AO in new renderers and seems that you fail to understand why we all still use AO to this day! And almost every movie you see out there with characters and environments has AO composited in either in a subtle way or otherwise. From scenes rendered with Renderman to Vray to Arnold! Which is why all high end renderers to this day include AO inside their engines and shaders, even if you are brute forcing GI with 100 bounces in your scenes!
Keeping in mind that the AO in UE4 is NOT the same AO used while compositing a scene with offline renderers, while it gives the same impression it is still a post process effect as mentioned above and is prone to lots of artifacts in motion and in stills as well as wrong shading. AO is not typically composited over the entire scene in a production, we choose which passes get AO and which don’t and how that also effects reflections.
In UE4 I prefer to turn AO OFF entirely and use AO inside the Material shaders directly baked in environments and characters, this also acts correctly since AO will also respect reflectivity or lack thereof when used inside the shader vs used in a post process effect, it is much more work to set it up this way which is why people just turn on post process AO which I think muddies up the image and creates artifacts.