lore-wise we basically liberated the moon from the Hive and yet we still have Hive there in HoW, no more no less. You could argue maybe Crota's army was too vast to comprehend, but if anything there should then be Wolves fighting for power vs other houses, maybe hanging out on the moon with the House of Exile too since they most likely scattered. Or maybe let us still encounter them during DLC specific strikes or story missions, maybe even allowing blades to return in certain areas? They have had missions before where you were essentially separated form the main open world server (ex: the first moon mission).