I think this is the one of the worst lumen Tutorials I’ve seen so far. Extremely biasing the reflection ray intensities and then messing up the desired material roughness values to compensate for it is one of the worst ways to go about it.
You are essentially completely changing what the original material is supposed to represent just in order to remove artifacts caused by combination of the technological limitations and incorrect sampling settings.
In real world, if you do archviz and client tells you “the table is not supposed to be shiny polished wood, it’s supposed to be matt finish”, then you are screwed because as soon as you increase roughness again, you will lose reflections almost completely (due to the excessive reflection ray clamping), in which case client will again say “the table is not supposed to be completely rough finish, just a matt polish, but not glossy”.
The fact you dare to advertise paid courses called “elite renders academy” at the end of showcasing such poor, beginner understanding of Unreal’s renderer, it’s a cherry of cringe on top 
My response may sound unnecessarily harsh, but it really frustrates me when people with merely the most basic understanding of things immediately start their own paid courses and academies these days, because it feels like its scamming other beginners out of money, for low quality information, and beginners especially are usually running short on money. 