What we really need is a scalable, distributed, physics pipeline so we can scale sims to 1000x realtime with billions of colliding objects. My guess is that Google/Stadia or Unity/UnityML are better places to do that work than Facebook, but if Carmack decides to learn physics engines* and make a dent I'm sure he will.
Until our environments are rich and diverse our agents will remain limited.
*More, I'm sure his knowledge already exceeds most people's.
Improbable tried to do that with Spatial OS. They spent $500 million on it. Read the linked article. No big game company uses it, because they cut a deal with Google so their system has to run on Google's servers. It costs too much there, and Google can turn off your air supply any time they want to, so there's a huge business risk.
Interestingly companies like SideFX are also doing really interesting work in distributed simulations. (e.g. Houdini)