From the Introduction:
Building a world is hard work. You need a map, you need countries, you need cities, you need histories. The list of things you need is long. Even worse, you need players who will read it all! You can purchase a world, but that is expensive and then there is a lot of reading. Again, its hard work.
This whole concept is to take that work away. Get a map that is already drawn. Cover it with countries and cultures that already exist. Just tweak it a bit and everything is right there ready to play.
It’s not just for lazy DMs, it is for any DM who wants to prioritise their time and focus on story rather than background.