Coming Home had been made before and Apocalypse Now and Deer Hunter different kinds of movies.
Don't get me wrong magic is cool. But a nervous mother singing to her child at night while something moves quietly through the dark outside her house? That's a story. Handled properly it's more dramatic than any apocalypse or goblin army could ever be.
Dad almost died of a heart attack in the middle of making Apocalypse Now the biggest movie of his life. It doesn't make you want to jump into that business.
There's also some element of coming of age during the Reagan administration which everybody has painted as some glorious time in America but I remember as being a very very dark time. There was apocalypse in the air the punk rock movement made sense.