But i agree that BfA's biggest sin was throwing so much pre established lore into a dumpster fire.
Between Kul Tiras, Zandalar, the faction war (and revisting Horde vs. Alliance Battlefields all over Azeroth), Nazjatar and the Black Empire, a more "conservative" could've turned that material into 2 (or even 3) expansions easily.
At this point i just feel like that the writers just wanted to remove any potential plotpoint that still exists on Azeroth so that even to option to focus on anything else but the cosmology chart is nonexistent.
The sad part is really, when you look at BfA and simply *remove* 8.3, nothing changes.
Literally nothing, the ending of fourth war in 8.2.5. had a bigger impact on the story than the defeat of N'zoth, because he did achieve nothing when he was freed and we had to expend nothing to defeat him.