Garithos and Arthas were from Lordaeron, if the Alliance are guilty of their actions, then so are the Forsaken, who claim they are the rightful citizens of Lordaeron (and who actually are the people who spawned those villains). Daelin was not backed by the Alliance, that's literally why Kul Tiras hated them in the first place, because they refused to answer Daelin's call to war. The Horde are also responsible for the state the Amani are in, since it's the Blood Elves who opened hostilities with the Amani, not Humans.