what's whith all these genres?

this desire to invent new genres for every vaguely new thing that comes along is a product of consumer culture infiltration, the focus being on packaging everything as new and shiny and modern and innovative, even though beneath the glitter and the gimmicks it's almost always just a soulless version of the same shit (or, in many superficially 'experimental' cases, another genre's same shit). if people have to use genre tags for the vaguest differences then fine, i'm coming around to the idea it's more of a symptom than a cause anyways, but i encourage all modern metalheads to keep in touch with the genre's history, recognise how new bands relate to old traditions, not get caught up in this obsession with an illusory 'newness'.

The desire to invent new genres in the metal community has less to do with marketing and more to do with identifying with a distinct subculture. It's an imagined community, nothing more. There's no substantial market for Wintersun, and their sellout status is only relative to the bleak obscurity of bands like Brocas Helm. Bathory is more famous than Wintersun, but that doesn't make Bathory a sellout.

Keeping in touch with history is fine; but adhering to it obsessively merely privileges arbitrary characteristics as truer than others.

All metal is a hybrid form. There is no "pure" metal. Black Sabbath could as easily have been called "heavy blues rock," or "doom rock." There's nothing absolute about the origins of metal; it's all just history. So, if in years to come, people begin treating "folk metal" as a legitimate genre of metal, any argument against doing so applies as equally to doom metal or black metal.
 
I would point to certain forms of death and black metal as being purely metal, in the sense that any non-metal influences have been stripped out and there's nothing you could point to as derived from rock music or whatever, in terms of song structure, melodic phrasing, percussion, vocal style, etc.
 
I'm not saying that metal bands aren't doing something new; but no metal, no music of any kind, represents a purity of genre. Viewed in an obsessive historical mode, all metal might be classified as "folk metal" since all music derives from folk traditions. Assuming that something pristine, called "metal," exists somehow in a vacuum, and then imports elements from other genres to create some kind of adulterated version of metal misunderstands the concept of genre and the development of music.

All music is adulterated. Accepting certain conventions as somehow purely metal is to ignore the conditions that allowed those conventions to arise. Rock music before the advent of metal was playing fast and aggressively; it's an illusion to assume that there exists a veritable boundary of speed or aggression which constitutes that we have entered the realm of metal.
 
Pardon me, but this is the first time I've ever heard of Powerviolence sooo..... please enlighten me.

Powerviolence is HEAVILY punk rock in nature and goregrind is super down-tuned and death metal influenced. Both are similar to grind but quite different.