We know that. We remember how much Alleria had to convince High Elves to even get involved in the affairs of men. We know that as soon as the High Elves had fulfilled the promise to Anduin Lothar that the majority of the race left the Alliance. And we know that in Warcraft III that only Kael and his magisters went back for help to only be able to come across Garithos that sentenced him and his men to death for daring to get help from the Naga who seemed to be the only ones at the time willing to help. Garithos sent them on hopeless missions hoping they would die before imprisoning them and sentencing them to death.
It’s only certain Helfer posters that try to pretend that it was anything else.