I think that discrepancy works in their favor, generally. It helps underline the idea that the Horde is a more loose confederate of allies--if anything, from launch day in Vanilla, the idea of the Horde having a Warchief felt like a stranger inclusion than the Forsaken and, later, blood elves. Certainly, a central authority figure having final say in military matters to keep this coalition united and focused works for the Horde's power structure, but immediately beyond the Warchief itself the Horde has no real centralized power structure--nearly everything beyond that is multiracial coalitions where the leaders coordinate their own things and make sure they don't get in each others' way.
That was underlined by the Forsaken and blood elves, and later, the pandaren and Nightborne. The blood elves don't generally seem to care where their allies come from so long as Quel'Thalas is secure, but the last we've heard, Forsaken reinforcements are still integral to doing just that, so Sylvanas has had Lor'themar by the short hairs for some time; despite their relationship rapidly deteriorating after she forced his hand on providing forces for the Northrend campaign, it took until Garrosh began actively worsening the situation for his people for him to consider the Alliance again. The Horde was, well, a Horde, a decentralized, disorganized wave whose allies didn't necessarily trust one another so much as got along because the alternative was standing alone against several global superpowers including the Scourge and the Alliance.
While I desperately wish the conclusion was arrived at with more grace and better character development for all involved, and didn't seem to default to Baine getting tacit support to make unilateral decisions in regards to inducting new allies into the Horde, the current council we have is what I felt we should have had since Vanilla, especially as the Horde began inducting more allies of convenience/necessity who didn't so much buy into the brotherhood-and-honor vibes Thrall's refounded Horde had in Warcraft 3, where the three leaders were all personal friends.