shadzar:
I think the main difference is that published settings (whether Forgotten Realms, Greyhawk or Wilderlands of High Fantasy) inklude a player section that preempts questions by giving or at least hinting at answers.
At one point, gms and players think alike: Both want the character to fit in as seamlessly as possible.
Many homebrews I encountered so far lack in this facility. They can´t help the player make an informed decision on what is possible and what not, what fits and what not.
Chapeau for the gm that not only creates a good setting to play in but also manages to ease the players into it.
Here´s one of he point the aforementioned question of "why" arises. Do I know everything I need to know to build a fitting character?
OTOH there are always people who are so afixed to certain ideas that they will never be able to fit their ideas into any setting if it is not the wildest kitchen sink, but that´s another matter.
I think we are walking down the same road, but opposite sides. So we are going to the same place, but haven't gotten together yet...
As I said with PoL, FR, etc has no game to it. The adventure is required.
You can Run the FR setting with an adventure Published in Neverwinter. The game is happening in Neverwinter, and you may have read some about it, but you don't know what is in that module.
Likewise a homebrew world is FR, and jsut the backdrop, but the action happens in the adventure.
There is no player section for most adventures that gives you advance details about what you will see in the adventure. It may offer a little about Neverwinter for those that don't know, but nothing to tell about the adventure itself as that is all learned through playing no matter if published or made by the GM.
I tried an experiment years ago replacing gold with steel bits, and people that had not played the setting thought I was crazy for coming up with such a thing. Later when told it was a published setting somehow they instantly accepted it and took back all their accusations of me making some crazy adventure.
This is my proof that people will see the published things a ok, while DM creations to instantly be questioned.
New players don't often question so much either as they don't have preconceptions of what exists or who is right or wrong, which is why I mentioned earlier to avoid the GM v player to new players. Some things you just have to learn for yourself.
So settings too, not jsut my point of adventures, are more often more readily accepted from the designers than form the DM running the game for you.
The designers are trusted more than the actual person in front of you.