Saves Time is easier

Saves on time, quicker

How it glows surrounding it

It also gives similarity to objects within the scene and some objects are used more than once, or rotated or scaled to fit in the scene

They also remodeled each building slightly, so that the scene works and does not look entirely the same.

The 3D model is the brown model underneath which has been modelled for the scene

Use of normal mapping and the right roughness can allow lighting to interact with (relatively) flat meshing realistically. This can greatly save from unnecessary modelling of every bump that may be on something like a rocky surface.

In the screenshot we can see quite a few efficient uses of mappings with the rock details and even the background is likely an image of a far off distant rock pillar. This allows scenes like this to have great detail and scale whilst saving on resources and render time.

Maybe get visual effects from a library.

Don't need to necessarily have roughness and need to interact with the environment

Doesn't need to be modelled.

Texture in this scene doesn't necessarily have to be reflecting light and be effected much as it is a cool visual effect that is not intended to be there for long