There are two comments, yours and another one, that suggest that I might not ever been a &quot;true listener&quot; of heavy metal. That&#x27;s the &quot;no true scotsman&quot; fallacy. Why can&#x27;t someone who sincerely enjoyed a genre of music in his teens outgrow it? No, better, outgrow the whole idea of genres.<p>Heavy metal is (you have to admit that) a pretty rigidly codified type of music. It requires a certain set of instruments, with few variations (I still remember debates in the eighties on whether keyboards were kosher). It mostly deals with a fixed set of themes. It sounds in a very recognizable way, so it&#x27;s rather easy to classify songs that fall into it. Performers dress in a codified way, also easily recognizable. (To all these points there are obviously a few exceptions here and there, as always.)<p>As for the richness of subgenres: it seems to me that these subgenres are just the partitioning of a fixed space of immutable size. The urge to classify them is another proof of the fact that the rules of the genre are so rigidly codified that the slightest deviation or emphasis on an element requires (or allows) a new classification bucket.