Skrillex didn't produce Scary Monsters and Nice Sprites.
In the year 2008, major labels Universal Music Group and Warner Music/Warner Bros. were trying to figure out a way to capitalize on the UK Dubstep craze and the US EDM Festival craze at the same time. They employed the help of Joel Zimmerman (Deadmau5) to scout for a pet project to help with production.
So Deadmau5 goes and finds Sonny Moore (Skrillex) who is the lead singer of the metalcore band From First to Last. This was a good choice because he already had a built-in crowd (of the same demographic that would be pulled into EDM, mostly scene/hardcore kids). The issue was that Dubstep, from an engineering standpoint (at the time) didn't have much going on in the midrange frequencies. So Joel goes and releases Skrillex's first "My Name is Skrillex EP" which sounds a lot like Justice. If you check the credits, John Oates is credited as a writer on the album (which was hooked up through his label). The EP does really well, so they take it a bit further... (cont)
So Joel with a bunch of capital investment from UMG (they own Mau5trap) goes and hires a team of ghost producers: Jon Gooch (Spor/Feed Me) and the members of Noisia to help Skrillex develop his first album (SM&NS). Sure enough, Noisia and Feed Me ends up producing 90% of the album and it does PHENOMENALLY well. It's still doing well. They managed to shift the composition of Dubstep into what is called "Brostep" nowadays by designing it to have a significant amount of sound design in the midrange. The reason they did this was because at the time, Festival setups didn't have a ton of accurate low-end backend setup, so they had to make Dubstep sell well in a festival market.
Fast forward to 2011. After being pissed that he's being hooked up with a bunch of pop stars to bring Dubstep/Brostep fully in the mainstream, Skrillex fabricates a lie that he lost his laptop in Milan (even though he had pictures on Instagram of him producing his work on a desktop computer) and all his jobs get "leaked". Skrillex ends up getting fired by Mau5 and then goes to the next guy that injects him with production knowledge, Diplo. That's why anything after Skrillex's dubstep phase sounds wildly different. As for Noisia and Feed Me, they made a fuck ton of money and basically get to do whatever they want now. We're talking tens of millions of dollars, plus royalties.