No if you add the xml:base attribute.
I recently discovered the same issue with RSS feeds in Drupal. If I don't use absolute links for images for instance, the images will not show up in the feeds. I would rather use relative links. If xml:base is the solution, then this is a fix that should be added to the core Drupal code which handles RSS for <front> and taxonomy.
Psst, guess what? xml:base is *already* in Drupal's RSS feed. Very few feed readers support it because feed readers think only about RSS and Atom, and much less about XML or namespaces or hell, even doctypes.