Descartes' ideal of consciousness is the supposed experience of an eternal "God" who is beyond space and time. For this "God", there is no dispersal in time or space and so no integrating is necessary. All sides of an object would then be given together.
But this is precisely NOT our experience of "perception." Descartes' "God" does not "perceive" an object. Similarly, if every note of Beethoven's Fifth Symphony were "heard" simultaneous, it would not be the hearing of a symphony. The attempt to understand consciousness as analogous to a "God's eye view" is therefore doomed to failure.
Happily, the reduction protects phenomenologist's from this attempt, for we describe our consciousness of an object as it is experienced, not as it would be experienced by some ideal consciousness to which we have no access.
Because consciousness is experienced as essentially temporal and spatial, it can grasp an object only by an active process of integrating unities, of holding an object together as self- identical throughout its dispersed phases. Thinking of consciousness on the model of "God" blinds us to this active process, since for "God" there could be no dispersal; objects are always already prefabricated. Hence Descartes missed the essentially intentional nature of consciousness.
It goes without saying, of course, that this notion of "God" is the idea of an abstraction, not any actual God.