(I actually wonder if all of them were, to an extent, and whether the completely horror-free story experience is a relatively modern development.)
Thought experiment: take the plot of a modern horror film (such as one of my recent favourites Nope) and imagine retelling it in a simplified fairy tale style, preserving the horrific events. What you end up with is much more like an original fairy tale, before the modern adaptations that made them “safe for children”.
All of us have a nameless fear of the dread and a darkness inside and it seems to me these sort of movies/stories over-stimulate this part of our mind/brain which i don't think is healthy for the society and the individual.
But not nearly as scary as the person who generalizes "I personally dislike something" to "it must therefore be unhealthy for society and other individuals to enjoy it".
The latter tends to kill more innocents in the long run.
The psychological effects of prolonged exposure to extreme gratuitous violence in horror films (the sub-genre of torture/sadism/slasher) are well known. The effects are quite detrimental (particularly in youngsters/teens) and in many cases long-lasting. They include Persistent Anxiety, Fearfulness, Avoidance, Obsession, Desensitization towards Violence (especially towards Women), Lack of Empathy, Nightmares, Sleeplessness etc.
Scary movies can have lasting effects on children and teens, study says - https://record.umich.edu/articles/scary-movies-can-have-last...
Psychological Effects of Horror Movies - https://edinazephyrus.com/psychological-effects-of-horror-mo...
In my comment's defense, it at least didn't mistake an article from the Edina High School student newspaper for a scientific study conclusively demonstrating the effects of prolonged exposure to extreme gratuitous violence in horror films.
I might also add that the details there are from certified Psychologists/Teachers employed by the School (AP Psychology teacher Heidi Mathers and Edina High School psychologist Samantha Bialozynski). It is highly relevant since it talks about the effects on school students/teens who are the primary market for the horror film genre. These psychologists have more data and are in a better position to observe behavioural changes day-to-day than in outside studies.
I don't think you are capable of understanding more nuanced studies done by NIMH etc. However, i did give a well-respected and often-cited study by Kristen Harrison and Joanne Cantor in the other link. You are encouraged to read the original study (mentioned in the article) for edification.
Some people thrive on routine and familiarity, and I'm the opposite (neophilia).
Extract:
"That was a period vastly longer than the civilization which has brought us a growing security against the beast that prowls by night. And the beast remains part of our heritage, unforgotten; it pads through the dark back-ways of our minds, peers out into our dreams. There is a kinship, a bond, between it and us. It's part of the raw substance of life; if necessary, we'll create new forms for it. As the original monsters of the environment dwindled into relative insignificance, man invented mythological terrors to replace them, new heroes to confront his inventions. It was as if he sensed a lack-and dragons and griffins, werewolves and vampires were born to hunt the outer dark again and restore to it what was missing."
Did you chat face to face?