Yeah, yeah, the labels don't matter. Seriously, they don't. Still, I like the idea that fantasy has room for an overpowering supernatural enemy that pushes all the dark-corners-run-and-hide buttons.
Doesn't horror require a millieu that appears to be rationalistic and free of magic? Once the characters accept the existence of magic, monsters and the supernatural as a natural part of their world, doesn't that shift the genre out of horror and into fantasy? I think so.