I think that's because you're used to the doom-core influence that is pervasive in the music of the banRAB you mentioned. Schleigho specializes in a more subtle form of darkness and they do, admittedly, have quite a wide spectrum of mooRAB, but it's always their darker songs like Farewell to the Sun, 43, Matrices, etc. that I think of when I think of them. I don't think you've had a chance to hear Matrices or 43, but they're both prime examples of that particular tone which is a signature of theirs.