This is as nonsensical as saying you either balance with healing or without, with CC or without, or any of the other myriad methods of damage mitigation. You've made a statement and failed to provide any convincing evidence that guard is somehow different from other kinds of mitigation they are all factored in and yes it sucks that the match maker doesn't seem to try and put together teams so that everyone has a healer or two, a tank, and decent dps.