Don't try to educate me on genres of music because it's a retarded argument. AC/DC and Zeppelin were hard rock 30 years ago when there was nothing harder, now they're classic rock. Hard rock now is simple pop riffs and song structures made more aggressive (ref; Saliva, POD). Alt metal is a way of saying nu-metal without the negative connotation, and it is basically heavier hard rock with screaming. But whatever you want to call it, it's not 'pure american metal'. It's pop.