Because musically, the store's fanbase has already created this sort of...trendy standard for what is done by bands. Whiny vocals, core vocals of some kind (deathcore has become really big), breakdowns, etc.
I'm just saying is all. I was being slightly sarcastic, but mostly going off of what I've seen happen through that store and it's average shoppers.
EDIT: In response to Arch Benemy, I know Trivium are not musically like those bands at all. But they certainly have the fanbase. Much like Avenged Sevenfold and Disturbed have gotten.