Most communication throughout history has been ephemeral, and lost as soon as the people relevant died without relaying it to someone else. Consider the 1800s,

Most communication throughout history has been ephemeral, and lost as soon as the people relevant died without relaying it to someone else. Consider the 1800s, where much of our understanding of the attitudes of the day comes from newspapers and archived letters. Then consider how many more were discarded once they had served their purpose. Today it's possible to archive all of that ephemeral information, but it has never been necessary. Usenet, for example, was thought to be ephemeral because at best you had a few months worth of posts archived on your server and maybe your local machine, so if you said something boneheaded, it was going to naturally fall off the internet sooner rather than later. As it turns out, that was an incorrect view of the world. Most forums are treated by their users the same way; a place for people to meet and talk about things in quasi-realtime, but not to archive those discussions for all time. Of course, as it turns out, those discussions are archived for all time, or until the forum closes or has a catastrophic data loss (e.g. this one we're on now).