I'll freely admit I'm not a follower of Golarian, so, this is the first time I've ever heard those words.
Funny thing is, I don't follow Planescape, but I know what Sigil is. Are these areas as key to Golarian as Waterdeep, Greyhawk or Sigil is to their respective settings?
To be fair, there are lots of settings that don't really have a "hub". There's nothing wrong with that, but, it does make it somewhat harder to jump into the setting when you don't have one. As an outsider, I have no idea, for example, of where I should start in Ravenloft. Strahd's domain seems like the right spot, but, I really don't know. Eberron seems to focus a lot on Breland, and Sharn definitely seems to encapsulate a lot of the setting.
But, at the end of the day, maybe it's simply my lack of familiarity. How many adventure paths have there been in Golarian and how many focus on Absolom?