Disappearing content is a blessing, not a curse. Let it all be replaced by new people doing the same things slightly differently, instead of constantly having to confront prior art.
As another example, I keep every line of code I write (that wasn't written for an employer) forever. I often pull up code that I've written decades ago to use in new projects.
The beauty of the internet is that the old and the new aren't mutually exclusive -- there's plenty of room for it all.