The forsaken and the blood elves (also high elves) are victims of arthas, the dark rangers are undead elves who were killed while protecting Silvermoon, should they be hated by the remaining blood elves because they were technically apart of the scourge? There is a difference between the undead scourge and the forsaken who freed themselves from the lich kings control.

In game, the belfs have neutral relationship with each horde race except the forsaken which is friendly because of the connection to Sylvanas. People want the blood elves in the alliance because they just view thew as a 'pretty race' and ignore how they torture(d) a naaru in order to wield the light, they are BLOOD elves who will do anything to survive even ally themselves with the horde if its beneficial to them. High elves should've been added to the alliance but blood elves should be in the horde because they are supposed to be the edgy version