It can be created. The present Wiki RSS feed program has no parameters, but others do. For example, tiki-blog_rss.php has to be told the blog ID to return data for. One could even add an optional second parameter to specify what kind of data should be returned by the RSS feed, as there are several possibilities: Page's entire contents, changes made, change description, permissions. Yes, they all could be returned every time, but you might want to minimize the overhead for RSS feeds and some people might have 5MB pages.