Why the OSR likes Metal [speculation]
Growing up, music was a huge part of my life. In elementary school I sang in a boys choir, and then in middle school, high school, and part of college I was in the band, in addition to doing some singing here and there.
In middle school, I had a pretty exceptional band director, Mr. Ruiz. He was so passionate about music, and would rage from the podium in that wonderful way where, though his voice and demeanor were intense (and perhaps even disconcerting or even frightening for some people) the root of his rage grew from a place of great compassion and care. "You can do better! Stop holding yourself back. Practice! Don't give up! Don't be lazy! Feel it! Improve!"
One day while preparing for a performance (probably UIL, but I sadly don't remember), he stopped us all suddenly saying "No no no no no no!" He directed specific comments towards the brass, woodwinds and percussion, and then said something I'll never forget:
"Music," he said, "is like life. It's all about tension *pause* *pause* *pause* and release. Tension... and release."
The problem, as I now recall was that we kept fumbling over rests. We weren't respecting them and staying quiet for their full duration, and he stressed their importance, and the way in which the silence can actually be used by the composer to build tension. Build anticipation.
The ongoing refrain I hear in the OSR is player agency above all. Meaningful choices. Real, in game risk. With justly failure and poor decisions.
Because the risk is real, and because there is no set story, no one at the table *actually* knows what's going to happen. On top of that, because the players and DM (I think it's safe to say) are rooting for the characters to succeed in the face of terrible terrible danger, or die gloriously, the tension can become enormous as the game goes along.
Railroading is like playing a video game with the cheat codes. There's no risk. It becomes boring. Pointless even. If you already know what happens, why have me pantomime along? Just read me the damn story and be done with it.
Metal then, as a musical genera seems to fit this mentality better than most any other musical genera out there because it can take work to enjoy. Fifteen minute songs can drone along, creeping through the sludge. Guttural vocals and dissonant, chaotic passages can seem to actively fight against the listener, but then... the tension breaks and a metaphorical sun shines through the clouds.
Take for instance this track by Temple, Rising from the Abyss:
I can tell you now that there is extreme beauty at the 6:27 mark. Extreme. But it's very simple. It's not fast. It's not glorious, speeding arpeggios, but the first time I heard it it stopped me in my tracks. I wanted to know more. I wanted to know why I thought this spot was so fantastic, and after listening to the track closely, I realize that 6:27 is so damn good, because at ~4:15 a journey through a repetitive wasteland begins. It's not actually a wasteland of course, but it's very radio unfriendly, and all it's really doing is building, and building, and squeezing, and intensifying, and building even more. Ratcheting down, tighter and tighter until finally, at 6:27, the sun breaks through the fucking clouds, and everything resolves.
Now see... if you just started at 6:27, it would suck. Or at least not have the same amazing quality to it. The journey shapes the track. Like the journey shapes the game. The excessive risks of terrible body horror in the Teratic Tome build the tension for the characters and the table. The player agency makes it all real.