i mean, to be fair both are right.
in the faction conflict plots, after the battle for undercity where varian started the world war, every single time the horde was the active character and alliance was passive or warped to ignore its previous acts (like all the stromheim plot in bfa, the attacks on the forsakens boats in wrath, even the varian's declaration of war)
in the big bad guy plots effectively the horde is irrilevant. to the point that they could be even cutted from the game and nothing would change.
probably the only exception is uldir, but take the entirety of legion, there is even a single horde character in the story? there are belves in the attack of suramar, thats all.