Heavy metal purism

[Becky]

Noun describing a mindset among certain heavy metal fans who are preoccupied with distinguishing between true metal and [false metal]. Typically, heavy metal purists dislike false metal, which often is taken to include glam metal, nu metal, [alternative metal] and metalcore.
[Heavy metal purism] tends to be more prevalent among younger metalheads, especially black metal fans. Practitioners of [heavy metal purism] are sometimes referred to as heavy metal purists.
Also often referred to as metal purism or metal-purism