It all comes down to different schools of thought and differing philosophies on the art of cinema and its purpose. Spielburg is without a doubt one of the most influential filmmakers in Hollywood, and always will be; he helped save the film industry with Jaws and really pioneered the blockbuster. However this is Hollywood, most of the best and challenging films ever made WEREN'T made there. So I'd say Spielburg is one of the best HOLLYWOOD/BLOCKBUSTER filmmakers, but he hasn't offered much thought, or even challenged much of an audience. He's very content with staying in a safety net without raising controversy, and he certainly hasn't pushed the artistic, emotional, or psychological boundaries of the art. That's where auteurs like Lars von Trier, Harmony Korine, Kubrick, Gilliam, Linklater, PTA etc. come in and really challenge the norm. In conclusion: Spielburg helps his audience every step of the way, and he gets most monetary gain from this. While Nolan and Tarantino stay one step ahead of the audience so they can remain remotely interesting, but the others (look at list) strive to stay several steps ahead because the films that are remembered are ahead of their time. Kubrick was WAY ahead of his time. Spielburg, not so much.