It has to be said—both systems have their risks. The risk of the Hitchcock-ian system is that you may stifle the creative force of the people who are collaborating with you. The film that results—even if it's a perfect vision of what somebody had in his head—can be lifeless: it seems to exist on its own, without the necessary collaboration either of the people who made the film or even, ultimately, the audience. It says: I am what I am whether you like it or not.
On the other hand, the risk with the process-driven film is that it can collapse into chaos. Somehow the central organizing vision can be so eaten away and compromised by all the various contributors that it collapses under its own weight.