People take for granted for how classic is an open world, with little to no portals between zones, limited to no phasing, every player is in that zone, you can see them regardless what quest they’re on, unless they’re layered.
WoD+ are all movies before video games. You are playing through a movie, every zone is Uldum. Very few quests tell you to go to another zone, even instance quests are put inside the instances now, you don’t need to take quest from one continent to do a dungeon on the other continent.
Each expansion makes the world smaller and smaller, more and more phased, to a point where i’m pretty sure a single zone could have 10+ phases depending on which part of the quest chain you’re on.
It’s not a world at all, its a series of connected instances, which are in turn a series of connected phases which are sharded.
At this moment, there are so many zones, but look at where players are concentrated, there’s so much fewer zones with players in them.
Look back at phase 2 of classic release, so much more zones were used, every player saw every other player, there is no sharding, you knew these people, and it was an actual world.
It’s a completely different game. Retail is not a “world” at all. Just a linear movie. And in shadowlands it’ll be even worse, since new players will all be in the same starting zone, and all go through the same movie sequence starting with BfA(which isn’t great).