Vertical progression MMOs can also be called "Ladder" MMOs. You climb the ladder, and when you reach the top, there's just another ladder or the wait for another ladder. You can also climb back down to the lower ladders if there was a spot you enjoy, but it's never the same as when it was new, and it never matters beyond its level outside of achievements and mounts.

There is never long term planning in ladder type MMOs or games. There's just the new season. It's the same day in and day out, except for when they change things by fundamentally altering or adding new classes.

The great thing about it is that it makes the game easy to pick up. It's not hard to climb the ladders, ever. The bad thing about it is that it makes the game easy to put down. They basically rely on the fact that it's so easy to pick up, the amount of people picking it up will outweigh the number of people putting it down.