It's a sort of an "uncanny valley" in regards to how it sounds to me. It's heavy music but it doesn't sound like how my brain is trained that heavy music "should" sound like. My teenage self got so into hardcore and emo that he didn't really have time or desire to listen to anything else at all*, and that means that music that doesn't fit certain tropes associated with that span of styles I can't really develop a taste for much like how someone raised in a country where cuisine is pretty mild would have difficulty adjusting to eating very spicy hot food.
For example this song actually kind of explains it, especially at 1:55:
Metal songs don't do that. Especially the subgenres that I can't stand the most lime power metal and black metal. I want to hear the breakdown and the mosh part but it never comes. And the vocals never sound right, because they're never hardcore style screaming. The vocals always sound ridiculous honestly. And there might even be some weird really foreign element like a guitar solo thrown in.
And even if a metal song mixes melodic elements...it sounds nothing like melodic hardcore. For example no metal song, even if it has male/female vocals sounds like this in dynamics. The song is entirely constructed from elements of hardcore and emo. You could construct one from elements of metal and some other melodic type of music but it still wouldn't sound "right" to me:
And even the heaviest and most chaotic music I like still doesn't really sound like metal and the shows are nothing like it, you basically never would see people dancing like this at metal shows because the type of beats and breakdowns are way different:
That's not even getting into how the most extreme stuff like emoviolence doesn't really share any elements at all aside from being loud... that's basically it. As a teenager I developed a mental state where that's how heavy music is "supposed" to work and thus anything that doesn't fit the criteria I basically reject to not being used to Boomer style.
*This is probably also at least part of why I don't like any rap.
