who the hell decided what is metal and what isn’t?

I recommend freeing oneself from the chains of genre altogether.

Humans have a tendency to turn descriptive language into prescriptive language. So what started as artists experimenting ends up getting categorized into market demographics that are easier to sell to. Separate communities who, in order to exist at all, need to create rules about who does, and thus who does not, belong. And so what starts as free artistic expression reflects off of the audience and becomes economic and social pressure to conform to these rules. We end up with bands making “metal” music for the sake of being metal, at the cost of true artistic expression.

Is an artist metal? Is an album metal? Is a song metal? Is a particular instrument in a song metal? Is a particular bar played by a particular instrument metal? Is it even about the music, or is it about other things? The clothes, the color schemes, the fonts, the lyrical subject matter, the community? Does any of it actually matter?