Why is dungeon synth (somehow) considered metal?
I do not consider myself am enjoyer of metal music in general, I just like a few subgenres like (symphonic and usual) black metal. After looking around different artists I found out many album intro/outros turn out to be dungeon synth-like, other times they have a dungeon synth track.
I am a fan of December's Fire and Solanum (I know they didn't exclusively produce dungeon synth.), yet since both were finished/discontinued projects, I ended up asking for some recommendations and somehow I got recommended literal metal bands. Not even black metal which is a tiny bit similar, so that low-key had me confused.
So that's my question, how come dungeon synth is considered a metal genre?
edit: of the answer is related to producing it, please explain it, I want to get into it