When one looks back through history, one sees that writing is always present in any society, whether it is the Mesopotamians, or the Romans, or modern-day America. Writing is relevant throughout history because it is an expression of thought. These expressions create ideas that spark other ideas, which spark other ideas, and so on. It’s a societal chain reaction.
Take, for instance, a scientific paper that looks to be published. When a paper is thoroughly examined by peer review, a fellow scientist may be inspired by the paper enough that he writes his own take on the subject later on. Through this, we can observe the interconnectedness of the community and the effect it has on society. This does not always happen in the same way. If the same fellow scientist created a paper another that same peer reviewer disagreed with, that scientist might write a rebuttal of the paper; the other scientist might also disagree with the idea expressed in the rebuttal, and write a “counter-rebuttal.”
This is not limited to the scientific community; a similar series of events unfold for writers who write fiction novels. Writers have a tendency to be critical of each other’s work, i.e. J.K. Rowling supposedly wrote a letter to Stephanie Meyer regarding her book Twilight. Again we see that she wrote something to a peer, and that peer likely wrote back to her, despite their relative distance. Writing begets more writing.
All writing strives to express an idea. Whether or not society deems it relevant is not the reason why one writes. We write because we want to express an idea; it is the exchange of thoughts that changes the world.