The threads and posts here never disappear, they are a learning tool for anyone who cares to search for, and read about any topic they like. It sometimes keeps folks from asking questions that have been asked, debated, and answered over and over, but not always.
You are certainly welcome to read and comment on anything you would like, but in a lot of cases, this stuff is just so old, that some of the posters aren't even here any more.
A convenient way to use the Forum, at least for me, is to mark all of the forums as read, thereafter, when you visit the site, you can click on "Recent Posts" from the main bar, and see everything that is new since your last visit. Once you review the recent posts, the forum automatically marks them as read, and you can keep up with current threads and posts that way, with people who are actively involved with the Forum and winemaking. Just my two cents...............