Have you ever heard an Yngwie album? The majority of his songs have vocals. Its not just Yngwie Malmsteen, its Yngwie Malmsteen's Rising Force, his band. They play metal.

There are Yngwie fans of all ages, so theres not just moshing. Haven't you ever been to a big METAL concert though? Its about the same. People in metal concerts (as opposed to 'hardcore') actually like the music, so they don't spend 3 hours slamming into each other acting like idiots. So what do they do to get into the music? They listen.