I think it's because it's a sticky topic - one people will use a lot. That saves it getting shunted off the bottom of the forum and getting lost, and people starting hundred of new topics about things that have already been answered (as we know how bad they are at looking to see if someone else has asked the exact same question three times already...
).
Edit: as a complete aside, I can't find anything resembling any of the radio buttons you mentioned, Anna. Am I broken? Nnnngngng!