Yeah, we "win" on paper. But look at the game. Night elves lost everything. Are near extinction canonically. Horde didn't have to give back ANYTHING. Not Aszhara, not Hillsbrad, not Darkshore, not Ashenvale - nothing.
Horde also did not pay for their crimes.
So they say Alliance "wins" - but never actually gets anything out of it. How is that "winning"?
Horde was allowed to destroy TWO Alliance capitals without repercussions.
I'm telling you, it doesn't feel much like winning.