I'd like to be able to use an authenticated feed in Confluence content. Currently the rss macro does not allow feeds that require authentication

http://confluence.atlassian.com/display/DOC/RSS+Feed+Macro#RSSFeedMacro-Authentication

This seems a bit redundant, considering that there is also a whitelist (in case I did have authors putting in feeds from sites I didn't want them to). Perhaps I've missed the point, but what makes an authenticated feed so different to a regular feed that it needs to be blocked by the macro?