In the last line of your comment is the very answer to your question… It’s an old tutorial. Usually, if there’s another tutorial that has newer, more up to date information, they will archive an older one. Prior to this version of CG cookie, you could find the archives on site, but now, a lot of them, if they’re still available, are on CG Cookie’s You Tube channel under the “classics”, I think.
and you’re right.. some do still have valid info… One I miss on the site itself is Jonathan Williamson’s topology videos. those are still very much relavent.