A very interesting review of The Classic Horror Stories by HP Lovecraft by Jess Nevins. He does go out of his way to not mention REH, imo. However, he does attempt to explain editor Roger Luckhurst's reasoning for why HP has not only survived, but "been assimilated by capitalist culture" as well as having literary respectability.
Jess is always interesting to read. The only reason I can think of not mentioning Howard is it might divert attention away from the point of how HPL survived and the others didn't. It's not like he doesn't know, if you've ever read his exhaustive and informative annotations of the LOEG books.