Some of the arguments in here is missing the forest for the trees.
The quality seen in this tech demo is most probably impossible for game development. It's a short slice that's probably around 400GB in size, but why did they do it?
Simply put, it's not only to showcase what the engine can do to help devs, but also market the engine for film/TV production, like what they did for The Mandalorian and Rogue One. That's where you need those film quality assets.
ILM used Epic Games' Unreal Engine to create virtual sets for 'The Mandalorian.' This enables filmmakers to capture visual effects in camera.
venturebeat.com
Games will use lower quality assets. The engine will run very well on both next gen consoles due to this regard. Stop trying to get PR to force-feed you what you want to know and think for a change.