The person you're describing doesn't sound like a purist, he sounds like a poser. It's like the girl I saw wearing an old school Deicide shirt in a very non-metal environment who immediately avoided me and obviously didn't want to say a word about it. Some people wear abrasive/obscure metal as a costume.

You're putting too much of this on metal purism rather than personal taste. I'm a fan of both bands to varying degrees but there are legitimate complaints to raise against Krallice and Agalloch, let alone Liturgy. The core strands of DM/BM have a different aesthetic sense to these bands. A band like Virus is non-metal…