Well, I know you find the game without faction war boring, we will probably never agree there, but I see your point. I even agree that a character that always "wins" is boring. If we had had a "Burning of Mulgore" as was possibly planned and cut in BFA that would have helped.
In the end I think it comes down to the split in the Horde, with good and evil characters somehow forced to cooexist and depending which side is in charge the "opposition" is a problem for the writers. However the role this opposition has, I think, directly correlates to what the writers actually want the Horde to be. Namely good.
Because it is only the good guys that make a move under evil leadership, the opposite does not happen. Baine sabotaging both Garrosh and Sylvanas is the most glaring case and we never see Gallywix or Sylvanas trying to sabotage the leadership of Thrall or Voljin.
This does invoke a paragon position for those good guys, basically telling the player "this is the right thing to do, do it!" and I can understand how that kind of a neon-sign pointer might invoke misgivings on the Horde side.
There needs to be a clear line for what the Horde wants to be, I think, that would solve lots of issues. If it goes evil then we can work on getting the good folks into the Alliance and not have them as grumbling oppositon in a faction they don't want to be in.
I assume that BFA was the prelude to that, with the Horde excising the evil parts and recruiting more goods (i.e. Calia). This will not make everyone happy for sure, but in the long run I think it would improve the narrative, IF they stick to it despite all the backlash.