Hi and welcome to Lemmying.
Old sublemmies exist only coz none clears them, works as archive.
Note, there may be another community of the same name on different instance - c/main@lemmy.blahaj.zone is different main to c/main@lemmy.ml or c/main@lemmy.ca. They all happens on different servers, but single login is enough to reach them all.
If You mean meeting people from lemmy.blahaj.zone directly. Don't.