I was raised in a "no scary movies! We don't like being scared uwu" household and it made me deeply unprepared for adulthood.
Adulthood is a state in which you need to get comfortable with being scared, because so much of life is scary.
You will not, in your lifetime, watch your horse disappear into the Swamp of Sadness. But you will see someone you love in need of help, and you will have to choose whether or not to provide that help, and you will have to accept when you try your hardest and still fail.
You will not, in your lifetime, be menaced by the Wicked Witch of the West, or No-Face, or Ursula - but you will learn that people in your life can become monstrous and untrustworthy when they don't get their way, and you will need to stand against them.
You will not, in your lifetime, become cursed by the iron-ball rot that drove the boar god Jigo into a frenzy. But you will find out that humanity and nature are one and the same, and that rage can pass between them just as fatally as disease.
Children cannot live wrapped in candy-floss. You need to be afraid of fiction for the same reason you need to be vaccinated: so that you will be better prepared for the real thing.