That i’m fine with, give the Alliance a bit of Villian batting. I mean if the Horde still survive all the times they have been the bad guys the Alliance could butcher the Horde entirely and still be able to repent and come out looking fine.
This game is called Warcraft after all a game based on two factions fighting each other. If one side does all the fighting while the other does all the dying it wouldn’t make for a very good game. AKA BFA
Again this is the writers basically bending the story to Justify Anduin precious little outlook. While it also requires him to ignore everything else the horde is doing during the war.
Boy you love to speculate, Again this is just the story being badly written and thus makes Anduin seem like a stupid character.