Believe it or not, it's a skill to scream well. But you have one of the most common reasons for discontent towards metal...it's just screaming, anyone can do it.
It's not that simple, but most of the people who make the argument that it's just screaming probably won't be swayed to believe anything else.
explain how it isn't just screaming
if I screamed about how I ate macaroni and cheese for dinner it would sound the same as this garbage
and hey nobody is dissing metal just this screamo stuff.