Unreal engine does it good yes, however people need to take a step back and realize that it is created to be an engine good at a lot of things.
COBRA that runs Elite Dangerous is an inhouse, engine, meaning they have access to every part of it, and can build parts for it to do specific stuff, so there is no reason why stuff couldn't look this good as well.
That said this is a video not actual game more a cinematic, looks great yes and unreal engine 4 is insanely powerful but 'not' using unreal engine 4 isn't a bad thing.