More thoughts:
Shadows Fall cannot possibly be the "worst band" on any planet that still contains Trivium.
Hardcore vocals - and this is near-impossible for me to describe in writing - are kind of like "sucking in of all your breath while bellowing." Does that make sense? It's a "barking-like" sound. It sucks. Unless paired with actual hardcore music, in which case, at least it belongs. Take Lamb of God for example; I've always maintained that musically they pretty much rip. Their riffs are as good as anyone's of late. But those vocals! They suck!
Death metal growls are FAR MORE varied, they can be more high-pitched (a la Jeff Walker of Carcass), they can be the deepest of growls (a la Karl of Nile), they can be a mix of the 2 (a la Maurizio of Kataklysm), etc. Far more talent goes into your "standard" death metal growl than the shitty hardcore barking.