Hidden subscription link on Google Groups

It’s strange. When you visit a Google Group and are not logged into your Google Account (if you even have one) you might get the impression that you cannot join that group. If you’re already a member of such a group, you’ve perhaps noticed that you can unsubscribe from it using a <groupname>+unsubscribe@googlegroups.com email address. At first I thought replacing “unsubscribe” with “subscribe” would allow me to join <groupname>, but for some reason Google didn’t stick to that pattern. Instead it’s <groupname>-subscribe@googlegroups.com

Why such a link isn’t shown on each group page is beyond me, but at least it is hidden in the the documentation.