It's not about losing, it's about losing to give the Horde their story without ever come through for the Alliance.
The Worgen get invided by Sylvanas, fight back, get told it's lost and get shipped of to Darnassus, end Worgen story, just to give Sylvanas her Silverpine story.
The Alliance follow the whole of Stonetalon Mountains a bomb to try to stop it, to fail and see it drop on a Druid school, to give Garrosh some screen time.
The Alliance are told they lost at Andorhal and are told to leave, to give Sylvanas some more screen time, after that we are questing for the Cenarionn Circle together with the Horde.
While taking the whole expansion orders from an Orc, the former Warchief of your enemy.
Where were the Alliance racial leaders at that time in the story? non-existant