Old Threads Still Here That Are Closed BUT On Related Topic Side Panel

Was reading a discussion thread, and noticed on the right hand side panel of the screen where it said Related Topics, ( or something like that), I saw a few threads I thought I might also like to read.  Except when I clicked on the link to the thread, on two of the ones I clicked on, it read  that they were closed to replies.  So just readable, and not open to reply.  I guess archived on this new board, but there was a lot of posts in them.  If it’s outdated, not sure why still there, and if relevant, I’m scratching my head as to why no replies allowed.