I'm sorry, but I'm not following. What does whether the author of the post (or the article) is still around have to do with the fact that some topics remain relevant for decades or even centuries? We study, learn and use grammatical rules, literary techniques etc. created by people who passed away over half a century ago. This is an online community, so it's based on the interaction of a group of people. Whether one of those people leaves the community or is unable to continue participating in the discussions for whatever reason should not have any major impact upon the flow of the discussion, regardless of whether said person is the topic starter. Furthermore, due to the slowly-changing nature of the niche of this community (it's not a general discussions or a pop culture community discussing the latest news, but rather forums where we discuss the art and craft of writing), the topics being archived seems to be closed before their full potential has even been sought, much less reached. I've been browsing the threads from two years ago from the Writing & Publishing forum and see that many of them are as relevant today as they were then, and I could offer insight on at least half of them.