I'm sure that most of the time it will require a small team instead of one guy.
But, I think you overestimate the quality of a Hollywood blockbuster.
Imagine if you put Steven Spielburg in front of a hypothetical movie machine. A machine that could automate everything down to the actors and voices, so all the director had to do was write the script, place everything, and direct all the action (yes I realize something like this is years away). I'd bet that he could produce a movie at least as good as the average summer blockbuster.
Indeed, film is not just all direction and writing, handed down from above, and the rest falls into place. Directors often work with the same groups of people on their team, and it's not just because of nepotism or working familiarity -- Christopher Doyle brings as much to each Wong Kar Wai film as the director himself; Bela Tarr leaves the music completely up to Mihaly Vig (an integral part of his movies).
But, I think you overestimate the quality of a Hollywood blockbuster.
Imagine if you put Steven Spielburg in front of a hypothetical movie machine. A machine that could automate everything down to the actors and voices, so all the director had to do was write the script, place everything, and direct all the action (yes I realize something like this is years away). I'd bet that he could produce a movie at least as good as the average summer blockbuster.