What makes the black and death metal harsh vocal styles so effective is the fact that the techniques themselves are merely a mask, or more specifically, a verbal coating that imbues in its host specific tonal attributes which are designed to match the emotional and artistic aims of the surrounding music. Importantly, these two types of vocal distortion do not limit the (skilled) vocalist’s range of expression to the degree that the hardcore style does; instead, the black/death metal vocalist—much like the traditional opera vocalist—injects an extra degree of emotion and immediacy into his/her tone by pushing his/her voice to a physiological extreme while still maintaining a level of tonal control that allows the singer to match the dynamics of the music. This is especially important in most metal music, which is wild, stormy, and Byronic by nature, and it is precisely why the hardcore vocal style is inherently incompatible with the major forms of metal.
To explain further: aside from its typically questionable tonal (dis)agreement to the rest of the music, the physiological process of producing hardcore vocals simply limits the singer’s ability to match the dynamics of the music, as the process itself is not a type of coating, but rather, an almost singular distortion effect whose only true sense of variation comes as a result of specific individuals’ physical characteristics. In practice, this vocal style gradually grates and dulls the listener’s senses with its repetitive one-dimensional attack instead of exciting and inspiring emotions alongside the ebb and flow of the surrounding music.
Though the hardcore vocal approach is admittedly acceptable in the less-dynamic types of music from which is spawned (originally, hardcore punk, and later, grindcore alongside industrial), it is completely out of place in the more dynamic methods of metal (read: the majority of the genre’s respectable forms). Unfortunately, frivolous genre-mixing is one of the outstanding crimes in modern metal, and the maddening results are vocalists that have a tendency to mar what might potentially become outstanding art (see: Neurosis and their many clones, Ephel Duath, Gnostic, etc.) with their tiny vocal range (often bordering on a dull, mind-numbing monotone) and simplistic, ridiculously rigid phrasing.
What can we do? For one, we can help stop the madness: do not support that which does not support the values of metal (i.e., the wild, spontaneous spirit that flows through nature and is channeled into many of metal's greatest works), for the moment that music becomes monotonous and predictable--as it tends to when prominently mixed hardcore vocals smother mismatched music with their lifeless, stony weight--it has abandoned the realm of true metal.