Light Component Vs Shiny Material. When to use?

Hi! I’m still new on UE4 and I’m using the latest version.

I’m watching this video tutorial on YouTube, trying to make a simple endless runner game.

There is the comment below saying that you should not use "light component", and you are suppose to use "shiny material" instead.

Can someone tell me why "shiny material" can make better result in this?
How to know when to use the "light component" or the "shiny material"?

Emissive materials by default don’t affect the surrounding objects, so it’s much easier on the CPU, since it’s doesn’t have to calculate light.

I see, I get it Thanks