Garithos. Garithos exists as a character because of the decisions of Sylvanas and the other elves. So while she doesn’t hold all the blame, she was a part of it.
Emphasis mine. AFTER. Let me tell you the Story of Garithos, and how he was created from the actions of a living Sylvanas Windrunner and her people.
Garithos and his family lived in town near the borders of the elven kingdom. In the Second War when the Horde raged that far north, the elves all broke their oaths to help the humans(promises they made after getting the human’s help with the troll wars), and shut themselves behind their walls and said “not our problem”. The only elves to speak against this were Alleria and her loyal followers. Sylvanas even tried to talk her sister out of leaving.
Because of this Garithos’ entire town and family were slaughtered while the elves stood by and did nothing. The civilians literally ran to the elves and got shut out of the forest through the gates, refused entry. And there they were slaughtered, while the Rangers, Sylvanas included, stood by and watched.(Literally close enough to see it happening) Then when the orcs entered their lands and attacked the elves, they then cried to the Alliance for backup, which the Humans then gave.
This is the reason Garithos grew to hate the elves so much he became a racist. He blamed them for breaking their oaths and watching his family and his people get slaughtered on their doorsteps while they did nothing to help. The thought was this was a Human problem, and the elves did not care unless it affected them. Sylvanas did not speak out against this way of thought, not until after the Second War was over, not until after she already tried to stop Alleria from leaving to help the Humans.
Then during the 3rd war, she did speak up, but her and her peoples’ actions had already led to the creation of Garithos. The Scourge comes through and he is one of the last high ranking individuals left in the Alliance and is able to rally enough men and succeed enough that he was actually pushing the Scourge back. That’s right; slowly but surely Garithos was winning. Then the Blood Elves came down and said hey we wanna help, and despite his hatred for them he accepts their help. He then sends them on a tough mission, some say suicide mission, but one that was absolutely needed to win the war.(This is the same as Anduin’s suicide group sent to enable the Dazar’alor attack btw, but no one seems to make that connection), and the Blood Elves get angry and side with demon snake ladies, which Garithos is not cool with so he locks them up in fear that these elves he hates are just gonna make things worse.
He then later allies with Sylvanas and her forsaken, despite his hatred for elves, to help finish the war and re-take Lordaeron, with promises that they would not fight one another after. And that Sylvanas’ people would be free to make their own way, free of attack from the Alliance. Then as soon as he wins the war for her; Sylvanas slaughters him.
That’s Garithos’ actual story. He might have been a racist, and he is 100% wrong for it, but he was made that way by Sylvanas and the elves’ own actions and choices, and they also share in that blame.
A living Sylvanas helped to create the monster that was Garithos through her own actions, and then later betrayed and murdered the man, even after he was putting aside his own hatreds(some say justified) for the greater good.
And yet Sylvanas is still viewed as heroic in her life, and even un-life to some, while Garithos is reviled as one of the worst villains of Warcraft history.