In the Shadow of the Suyn with it´s condemnation and aknowledgment of Belves not being aware not much less accepting of Kael´s deal with the Legion says “Hi”.
Heck, both Taethelan and Liadrin mention in their dialogue several times their goal of taking Belf society FAR AND AWAY from the mark Kael´thas left on the kingdom… you know, the one related to him consorting with demons.
I repeat: and this concerns the Belves how exactly, dude? The demons pretty much IGNORED Quel´thalas during the whole freaking invasion o0f Azeroth, why would they care now?
Alleria´s opinion is just that: her opinion. NOT a “proof” the Blood Elves follow her sentiment -and considering most are happy to be were they are even post BfA… me thinks she´s still in the process of adjusting to the changes, nothing more and nothing less.-
You know what´s the big difference between BOTH cases? In regards to the Horde, the other HORDE allies joined in the efforts to dethrone the abusers… in the case of the Alliance and the Humans, NONE of the other races did anything nor gave a rat´s butt over the Belves.
The sky of difference between perceived betrayal and ACTUAL betrayal. Simply put it, even with antagonistic dictators, the Horde as an allied political entity came up to support the elves. The Alliance did nothing in the best case or outright validated the abuse in the worst case.