Everybody is right in a sense. Here is what I understood from it:
When you access a rift in the battlefields a random area is created. This is one area from a nearly limitless amount of areas. Once created the area stays as they are and belong to that rift and monsters do not respawn. So when there are a maximum of N rifts you could end up with N different areas at the end of the game.
If you replay the game then you will end up with N different areas at the end of that game.
However the replayability is reduced as the random quest generator is out, so there are no new quests in the random generated areas.
