Again these are called story threads. They write them, some get picked up in the future and some don't. Like the example I just gave you.
Like I"ve said now for the 3rd time, they might of had a vague idea they wanted to go to the Shadowlands. In that sense the story is at the mercy of past narrative leads. They pointed the ship in certain direction. But there is no way the concepts were fleshed out back then. Blizzard just doesn't have that level of consistency in their writing. But that point is also irrelevant. People aren't mad because we ended up with the Shadowlands. They disliked the details that have been fleshed out this past expansion. Which are the responsibility of the current narrative lead.