If fairies are immune? Dragon says goodbye to perfect coverage.
Dragon+Fire and Ground creates perfect type coverage. Which, surprise, surprise, basically every Dragon gets.
You're also assuming that Fairy will be resistant/immune to Fire and Ground. Dragon will still have nearly perfect coverage (Air Balloon Heatran spells doom for many), but Outrage will simply be less viable.
I'm not easily impressed; I'm usually oblivious to whatever's in front of me.