I think I read that Meta decided that the the higher resolution and pixel density was going to challenge the current and near future slate of GPUs, and decided to focus 
on edge to edge clarity. There is also the cost, as the Aero + sensors + hand controllers is substantially more.
An area where the Varjo is better hands down is foveated rendering compatibility. Meta could be definitely improve upon their implementation. I know that once I have the Q Pro on my head properly, I can look around a cockpit with my eyes, instead of my head. But that’s probably the lenses and not foveated rendering.