I’m not sure where you’re getting this from other than conflating chronicles saying that Sylvanas was interested in that land into Sylvanas wanted to start that war. Garrosh still started the war, Garrosh was still planning on using the Forsaken as a sacrificial charge to maybe weaken the alliance defense before the troops he cared about attacked.
Sylvanas took over the invasion to protect her people from Garrosh.
Well, yeah, since the story seems to be predominately be written for the Alliance players benefit they tend to ignore or whitewash any misdeeds alliance figures did in the past.
And I get the opposite opinion, maybe you just have a strong opinion of the character and that’s flavoring the way you read that story in a way different from how I read it.