Extreme forms of metal will never be popular in the mainstream, we know this. But why? Science has the answer. According to Mic.com:
A new study, surveying more than 500,000 albums, shows simplicity sells best across all music genres. As something becomes popular, it necessarily dumbs down and becomes more formulaic. [..]Researchers from the Medical University of Vienna in Austria studied 15 genres and 374 subgenres. They rated the genre's complexity over time — measured by researchers in purely quantitative aspects, such as timbre and acoustical variations — and compared that to the genre's sales. They found that in nearly every case, as genres increase in popularity, they also become more generic.
"This can be interpreted," the researchers write, "as music becoming increasingly formulaic in terms of instrumentation under increasing sales numbers due to a tendency to popularize music styles with low variety and musicians with similar skills."
So, here's why bands like Five Finger Death Punch, All That Remains, Attila, and to some extent Ghost do so well. The music is relatively simplistic and similar, sonically, to other music that is popular thus bringing an aura of familiarity to a listener, making them more open to listen to it.
This would also explain why certain bands are "ahead of their time," bands like Death, even Cynic and Meshuggah. At the time of their arrival, their music sounded so different, it was hard to grasp and ultimately rejected. It was only until like-minded bands came around that those entities influenced and gain traction.
All of this is just a roundabout way of saying, if you truly want to make it in the music business, technicality will not get you very far. You need to create something palpable. Of course, if you don't care about mainstream success and just care about creating art, then this article means nothing to you.
