Also, the former High elves did blame the humans for really petty things (i.e. the burning of their forests done by the forest trolls), and under the leadership of Anasterian Sunstrider, the race as a whole effectively abandoned the Alliance. Only the Windrunner sisters and various rangers wanted to continue their ties with the Alliance, but Anasterian still held his ground. Finally, when after the Scourge attacked, the High elves clung onto the Alliance once more; almost like a big middle finger stuck straight in their faces. I'm sure Alleria could/would understand the Alliance's resentment for the High elves after she went missing, but her race is not forgotten, and most likely, her ideology hasn't been swayed after killing a bunch of demons and fel orcs in the Twisting Nether either.