A Warchief was originally intended as just a tool for war. Since the position was invented by the Shadow Council just to have Blackhand as a puppet.
I'd say the Warchief position had a lot more responsabilities than just going to war after Warcraft 3
Diplomacy, Resource Allocation, Industry, Trade... Anything a nation, or in this case the Horde, would need to prosper.
All lore is a bunch of bullshit someone came up with. I mean someone at some point came up with the Idea that orcs weren't actually mindless evil people that summoned daemons from hell as in Warcraft 1 and were instead corrupted by the Burning Legion, as they were originally shamanistic people with actual feelings and individual mindsets.
That's how lore is written. Sure, sometimes the lore is inherently bad or they retcon the shit out of the story.
But I'd rather have Sunwalkers in lore than someone on twitter saying "Oh yeah, Tauren Paladins exist and they are the same as humans"