I guess I would boil it down to this:
if a highly visible and highly influential artist claims they are making an album in a new-to-them genre, and then they release an album that is not stereotypical for that genre, the only way it is possible that this album will actually change the genre in question is if it is a genuinely great album. Great in the way that all the greatest albums are great, totally irrespective of genre.
COWBOY CARTER is indeed that great.