So what? As noted, all sorts of non-SF material is lumped under "Sci Fi" by reviewers and Blockbuster clerks who don't know any better. That's sort of what kicked off the discussion.
And that's a straw man. There are also plenty of well-informed SF/fantasy creators and critics, including our own Greg Cox
and myself, who understand that a lot of speculative/fantastic fiction actually does
blur the lines between categories such as science fiction, fantasy, and horror. .
By coincidence, I spent the morning working on the cover copy for Shadow on the Sun,
an old Richard Matheson novel that has, at a various points, been marketed as either a western or a horror novel. Berkeley originally published it as a category western back in the nineties, downplaying the book's more fantastic elements, but I'm packaging it as a supernatural horror novel, complete with a Stephen King quote on the cover.
Both approaches are correct. In truth, Shadow on the Sun
is both horror and
a western . . . .
(And a fun, spooky book, btw. Somebody really needs to make a movie version.)