It's the other way around, actually....as Michelle Morrow (the voice of your precious Alleria in Hearthstone) and Red Shirt Guy recently confirmed on Twitter, the story of Warchief Sylvanas was completely ruined by Afrasiabi (especially with the burn of Teldrassil great idea) on PURPOSE because of his revenge, in order to make people hate her a lot just because she was a strong female character leader. Likely while in the same time inflicing genocide on the Night Elves because they were a strong mathriarcal race as well. This kind of decision and writing were likely all related to the Cosby Suite incident, too.
https://mobile.twitter.com/TheRedShi...64045787078660
https://mobile.twitter.com/michelemo...17673097330688
so as you can read, Sylvanas (and so, by proxy the Horde) were completely ruined and screwed over on purpose by the devs with this kind of writing, especially "thanks" to the SIN of Teldrassil that in the same time ruined Tyrande and the Night Elves as a mathriarcal race too... so as you can see Sylvanas as a character and the Horde too are clear victims of the revenge of the devs because of this reason, alongside the Night Elves too...
as for the Horde Council, yes, but it will likely be only good in times of peace, in times of war a Warchief will likely have to return to rule (at least temporarily) otherwise I think the Council will be too much "dispersive" in their decisions in a possible future faction war and so the Alliance will almost certainly strike first because of the passivity of the Horde leaders and gain the advantage...