Horror fans who got into gaming to scratch their horror itch once only had one viable option to satisfy it: tabletop RPGs. If it wasn't Call of Cthulhu, it was usually Chill or some hackup of Dungeons & Dragons. While we had horror-themed videogames during the '80s and into the '90s, it wasn't until "survival horror" got coined with Biohazard (better known in the West as "Resident Evil") that horror gamers really had a viable alternative. Since then, the bleeding that fantasy and science fiction TRPGs suffered for decades started happening in earnest to horror TRPGs.
The bleeding came by genre or similar preference. "Survival Horror" bled off the zombie fans, and not even the notable All Flesh Must Be Eaten could staunch that flow. Successive Aliens and Predator titles bled off those fans. The Half-Life franchise bled off more. While the post-2000 launch of Dungeons & Dragons, 3rd Edition had some impact, it wasn't enough to stop the tide- nevermind reverse it.
Though others may disagree, I find the critical success of Eternal Darkness: Sanity's Requiem to be the Point of No Return. Why? Because Cthuloid gaming, i.e. psychology-heavy horror, had a successful Proof of Concept outside of tabletop RPGs and that changed everything. This would be proven when Cthulhu fans had their own videogame: Call of Cthulhu: Dark Corners of the Earth (While not a commercial success, it was another Proof of Concept that videogames were now a viable alternative.)
But the core of a horror scenario is Monster vs. Victims. This is an asymmetric scenario, and tabletop games--both RPGs and boardgames--did this very well indeed. The boardgame world produced several such games, some explicitly horror and some not, with some form of asymmetry involved and used it to great effect. That sector of the gaming economy benefited accordingly, bleeding off yet more people from tabletop RPGs because a competing medium did what they wanted better.
It would not be long before videogames caught up. Something like this has been a popular gameplay option for horror-themed shooters for years. (e.g. Lead 4 Dead, Aliens: Colonial Marines) What's new is that it's sold as a product to itself, and what it means to the larger world of horror gaming.
The first attempt that got noticed was Evolve, where one player was the monster and the others were the monster hunters out to get it. The second to do so was Dead By Daylight, where one player plays a horror movie monster and the others are the survivors trying to escape it. In the past few days (as of this post), another game of this genre released. This is Friday the 13th: The Game.
For most horror gamers, they're after the experience of the scenario premise. They want to see if they could hack it if put in that situation; some want to be the monsters. The characters are fungible pawns, and Mech Piloting is very much the norm in terms of attitude; boardgames and videogames are far superior to what the majority of horror gamers want out of their experiences than what tabletop RPGs offer.
To say that the tabletop RPG world is oblivious to this development is to state that water is wet. You know how irrelevant they are to most horror gamers? (Or to most fantasy gamers, or to most science-fiction gamers?) Go into a livestream chat where one of these horror videogames get played, mention Call of Cthulhu by name. Wait. If you don't get crickets, you'll get "What's that?" or "That's still around?" Hey, you tabletop RPG folks, that response means one thing: IRRELEVANCE!
That's right: when the audience you claim to serve neither knows nor cares about your game, you're irrelevant. The future for horror gaming--Chaosium, I'm looking at you--is not in courting an audience that abandoned you because you can't deliver on what they want. You need an audience that does want what tabletop RPGs offer, so stop being dumb- seek them instead.