It's just a fact that there are not a lot of publishers who specialize in horror fiction. There are some publishers who do it, but not many that specialize in it. It's not a surprise since horror is a pretty small piece of the pie in terms of publishing.
Having said that though, it is certainly clear that there is a niche out there for people who know horror and know it well. Were someone to come along and specialize in good horror, and make sure they told that story well and stayed in their lane, then eventually fans of the genre would trust that publisher to produce things they like. It would be a "win" for the publisher because people might come to them first for their horror novels. It would certainly be a "win" for the reader since they would now have a place to go where they would be reasonably assured of having their horror-fix satiated.
GGE, of course, writes some horror...and good horror at that. "The Forsaken" is our first novel-length horror and it is currently with some folks for consideration.
If I were submitting it today, or if I were just looking for a good horror book to read, I would certainly consider Snuff Books and Severed Press.
Both tell their story well and the website and titles give the reader assurances that, if you are looking for a horror novel by someone who understands horror, then you have come to the right place.