Definitely an interesting question that made me think.

First, I would say directors are usually not praised for the acting of the actors, because it is not the directors craft that is shining. They are however praised for selecting good fitting actors and for giving those actors the right lines and scenes in order to shine, because that is their usual involvement. And of course the direction giving during the filming, as their title implies. The whole movie is the combination of a lot of smaller artworks and the skillful combination of those pieces is the art of the director and what they get praised for. Like a collage: the pieces are created by other artist but the skilful arrangement of it is an art form in itself, without praising the collage artist for the individual artworks.

The question in my opinion is rather if film directors in general are artists, because as you said: they don’t do it by themselves but rather rely on other people: actors, cameramen, cutter, editors… . And each single work could also be done by the director themselves instead of relying on other people.

And I would say: yes, film directors can be artist, if they involve themselves in the creative process in a significant way instead of giving every decision to other people and just being a producer with a different title. To refer to my prior comment: the intentionality is the artists touch. Like any boss of a creative team, like in video game production: it depends.

If Spielberg was involved in their movies in that way I cannot say, becausei haven’t looked into it. Probably they did and they are, but I cannot answer your specific question in earnest, because I don’t know.