for the same reason there's so many bad horror movies, it's a genre that welcomes a smaller scope, lower budget, dark lighting so it's harder to see said low budget, and game-wise bad controls are welcomed as a way to increase the tension
i don't mean this in a hater way, horror is one of my favorite film genres and i like horror games, they're just very accessible to make and you get all of the downsides of that fact with the upsides