Disclaimer: Yes, I know there are a few actual talented rappers and actual talented screamers.

I think that's why both generes became popular, because it opened the flood gates to a swarm of people with similar talents. "Hey! even I can do that! Let's start a band!!" Sorry, but anyone can rap, anyone can scream. Not everyone can pick up a mic and actually sing.
I can't stand rap, well, I REALLY can't stand the gangster rap. I can deal with the Will Smith type of rap music.

But I simply HATE the screaming rock bands out there. No singing, just this crappy grunting, screaming, bs, etc. It does however seem to be dying down a bit. I hope it finally fizzles out and goes away. I enjoy hard rock music, but I prefer my rock with actual singing, a verse a chorus, etc, not this deep throat screaming crap.