People (users) like to organize and categorize things in their surrounding. We like to build our own understanding of the world in chunks of information, as if we need to know how the world is. Some categorize things or information by color, others by shape, scent, sound, surfacing, shining or look.
As we do this categorizing of things or information we want to put it in another context - the linear (but not constant) timeline. When it happened is as important as what happened. We know that certain things happened during a certain period of time, and as the world is always changing - time is the only thing that can make us understand the world.
As when Bloomberg posted Steve Jobs obituary almost three years before his passing, is something that was world news then, but now - six years later - who remembers?
Time is crucial for users to understand the world in its context.