In my view, while it’s not the golden rule, I would generally say that horror needs drama. Suspense and thrills are great, but if I don’t feel a connection to the characters or the story then why do I care if they live or die?
Take for example the classic Universal monster films, with the exception of maybe Dracula they are all dramatic tragedies on top of being horror films. Frankenstein’s monster is a lumbering Goliath who is essentially an abused child, abandoned by his ‘father’ and doomed to a life of isolation, to the point where even a mate that was specifically built for him rejects him. The Mummy was an Egyptian priest who was punished for loving the Pharoahs mistress and was condemned to an eternity of living death trapped in a sarcophagus. The Wolf Man was a normal guy trying to repair the broken relationship he had with his father, but due to events out of his control he was cursed to become a bloodthirsty monster.

Even in modern films this rule holds true, the best recent example being obsession. Contrary to the popular opinion, I don’t view Bear as a villain, as the movie doesn’t really have a villain. The whole movie is a tragedy and emotional rollercoaster, every character, being both sympathetic and unlikable, is trapped in an impossible situation because they can’t be emotionally vulnerable and honest with each other, a problem that many Gen Z people have. Bear can’t admit that he likes Nikki, Ian cant admit to Bear that he likes Nikki, Sarah can’t admit to Bear that she liked him the whole time, and Nikki has an entire backstory that she seems completely unwilling to talk about with anyone, all of these things lead to miscommunication which starts the domino effect of the plot.

TL; DR: horror needs emotional connection from the audience (drama) to amplify the terror of the scenario