I think it would help to clarify that (in my opinion) Liturgy truly are not black metal. Wolves in the Throne Room and Krallice are closer, but Liturgy should not be classified under the black metal umbrella, and if they insist that they should be, I think that's a serious oversight on their part.
The truth is that over the past several years, a new genre has rapidly been emerging that has its roots in black metal, but is something different. Liturgy is the new face of this genre simply because of their identifiable differences from black metal. Other bands that I would deign to classify in this new category, but that still fall somewhat close to black metal, are: Fen, Altar of Plagues, Deafheaven, Castevet, Cobalt, to name a few.