If they’ve never heard of slayer that means they don’t really listen to metal so of course they wouldn’t know what to do with it. Metal is very hit or miss with non metal people. Even when talking about one specific band. I know plenty of people that have like a handful of metal songs in their playlists and it’s usually just one song per band and they dislike all the other songs that they’ve heard from those bands.

Tried asking them what they like about the songs and stuff when they asked for recommandations but the conclusion is always the same. People’s tastes are weird and make no sense.