They're kinda right. Metal wasn't really on the mainstream radar at all, it was just that cheesy 80's rock, plus Metallica. Linkin Park, Korn, all those guys brought metal and guitars back to the forefront during a time that hip-hop was more popular and they managed to draw in both sides of the crowd. Metal is a lot more accessible for kids today (I'd say a good 90% of my students are interested in metal/punk/hardcore) and they renewed those kids interest in finding more underground, extreme metal that still had more technical elements. A decade ago I couldn't give a student a Meshuggah album and now they're bringing that sort of thing to me.