I know you're the master of whataboutism, but I already said both factions actions are considered normal for a medieval fantasy setting focused on war. Though you are treating the old horde like its the same thing, despite the current horde being started by Thrall, a war orphan who was born into slavery by the alliance. And even then the old horde were conscripted by literal space demons who destroyed their planet & who were only there because they were chasing the Draenei.
Also the founding of Durotar was specifically not colonialism considering it was the expressed purpose of rebuilding the Tauren & Troll's homes who were destroyed by the centaurs & kul tirans, who were actually colonizing the area. The orcs were invited to live there.
Alliance are culturally colonialist. In that their actions aren't any different from the Hordes, but they constantly take the perspective of moral superiority.