It isn't by way of social standards that music is determined to be metal or not metal. Wouldn't a hipster come to a social standards conclusion? They use that in a vain attempt to deny the existence of any standards that are not subject to people preferences.
Physical laws are not determined by people, only revealed to the rest of us by the more astute among us. Ditto for good art work. The butthurt oversocialized and underconfident can't deal with such a cold, impersonal reality so they frame all of the arguments where people are involved to any extent in social terms, creating fallacious attributions and erroneous causal relations which result in bogus conclusions.
Hipsterism is another form of mental illness; a cognitive disorder encapsulating an emotional disorder at its core. They ought to know better and thus behave accordingly but they can't.