Jeez! I can relate to that entire "school population" crap stuff. My entire school is practically all jocks, preppies, and poseurs (aka the preppies/jocks who think they're cool because they copy so-called "punks", "goths", et cetera and claim to be "punk" and "goth")! But lucky for me, I'm one of those enternally ignored ones, so they (usually) don't bug me or at least, not anymore...But then again, that might be because I'm psycho...
And please, no offense to teh Slip-ness xD They're not THAT bad. I've heard much, much worse.
But yesh, anyway, most JRock to all JRock I've listened to don't sound even remotely like Slipknot. At all. Zilch. Zip. Zero. Nata. Nope, nope. Never, ever going to happen.
...Do ya get the point by now?
The only connection between some JRock bands and Slipknot that I can think of would be their "hard rock" to "possibly metal" sound, but they still differ.
I do so believe you need to expand your horizons (hee! xD) before you sputter out your ignorant and more-than-likely false "observations"...
But then again, I suppose it's just slightly better than everyone saying they're all just Marilyn Manson wannabees...