We must be listening to different worlds of music. What I get from this is that Metal is solely based around a grueling and an aggressive screaming vocal style, and outside of that, no other vocal style fits and will easily be grouped in with “nu-metal.” Maybe we should take a short look at Metal’s history?
Heavy Metal began with bands such as Black Sabbath and Led Zeppelin. Robert Plant set the stage with his melodic, upper-register powerhouse vocals. He was named the “Greatest Metal Vocalist of All Time” according to Hit Parader in 2006 (still very relevant) and various other sources such as Rolling Stone.
As Aerosmith led the way and paved a path for Hair Metal in the 80’s, bands such as Poison, Twisted Sister and Warrant took over the scene with their glam rock style, power ballads and music that offered melodic vocals. Not only did a lot of these bands LOOK like girls, staunchly covered in layers of makeup, long, delicately styled hair and tight feminine clothes, but some of the vocalist actually could have been confused for women due to their high-pitched vocals.
We enter the 90’s with Avante Garde Metal with the likes of (just to name a small variety) The Number Twelve Looks Like You with their spuratic, high-pitch shouts and screams, The Mars Volta with their melodic vocals, also mainly sung in an upper register, and Mr. Bungle.
What Mike Patton - the almighty God of Music - did for vocals (along with so many other aspects) in metal music is revolutionary. He killed a pre-conceived notion or standard in vocals with his effects ranging from operatic and heavy melodic swooning (hear: Pink Cigarette) to spuratic churping, screaming, shouting, and even Gregorian Chanting featured in “Goodbye Sober Day.”
With Mike Pattons direct influence in the forthcoming music, even his vocals in Faith No More, falling a bit short of Metal for the time, inspired the likes of Nu-Metal with his hip-hop vocals against screaming metal riffs.
Speaking of Nu-Metal…again, we may be living on different planets. With Nu-Metal making it’s wave in the late 90’s with bands like Limp Bizkit, Korn and Papa Roach, I can’t draw the connection to their rap-rock style and a female singing melodically against electric guitars.
When we take a look at sub-genres such as Death Metal, Doom Metal, Grindcore and Thrash Metal, there is no doubt that screaming/shouting/aggressive vocal styles take precedence against a more melodic approach, but many bands have bridged the gap and still weave intermittently between the two, be it male or female. If you take a look at today’s very popular Metalcore wave, it’s everywhere. And many of these male vocalist sing, again, in their upper-registers, just as Robert Plant so diligently paved the way to do so.
So, no, I don’t believe this argument holds merit. Screaming, while valuable to metal and hardcore music, is not essential to it’s existence. And if you “can’t take it seriously” because it is a female singing, well that, my friend, is sexism.