Why do old Creepypasta images (Smile Dog, Jeff the Killer) still look scarier than modern game monsters? How do we make that visual terror in our game character?

I’ve been thinking about how modern horror games rely so heavily on mechanics, AI, gameplay or sound design to be scary (like Alien: Isolation or FNAF 4). The monsters themselves are high-fidelity and polished, but they don't give you that visceral, psychological dread just by looking at them.
Meanwhile when i look at the og creepypasta icon , like Smile Dog, Jeff the Killer, or Suicide Mickey Mouse trigger my primal fear response through a single, static image that sticks in my brain forever.

How can we trick the gamer brain into experiencing those kind of terrifying look in horror game character design ?