Hello @Nick, @Andrew, and @L. Elias - great conversation here and great questions. I can elaborate and help you out. When you initially hit the DocOps site, we have a mix of public content, but we still have some restricted content. The messaging at the top of the main wiki page is intended to be there to just kindly remind people that if they want the "best" wiki experience, to log in immediately so you see all public and restricted content. That's all.
The reason for the messaging when you drill further down into the category boxes is to catch those people who still haven't logged in. For example, you don't see any of the Installing and Upgrading content until you log in, so the messaging is there. You'll also see this under Administrating, and Reference. It's a backup, if you will, to kindly prompt people to log in to see it.
We also have messaging when you get into the "Additional Reference Material" content other than the product docs. Such as: Jaspersoft FAQ, Oracle and SQL Server Whitepapers, etc. These docs are hosted on the PPM Support Page. The messaging is there because if you search for these immediately upon accessing the wiki, and you click the hyperlink, and you are not logged in to CA Support Online, you will need to do that to see that content.
So in summary, these are just "layers" of messaging to help protect that "restricted" content. If you are already logged in, just ignore the message and click the hyperlink in the text to see the content and you should be good to go!
Hope this helps!