What is it with the "you're all no one from nowhere" attitude. Being someone from somewhere, even if neither is very important, is part of being a character and how can one play a character without being one?
I don't think that's really what people are against (the 'someone from somewhere, even if neither is very important'). Unless the central premise of the game is that your character literally walks out of the mist with no memories or backstory (a really specific premise, mind you), people expect that your character grew up
somewhere and got to the campaign's starting point
somehow. The point (in those campaigns, in my opinion) is simply that none of that matters remotely as much as what they do
now, based on the events that unfold
as the campaign progresses. Your character is trustworthy and honest? Only if they show themselves to be. Same with sneaky and suspicious. Brave? Show that based on their actions when ratmen attack the tavern. Outside of forum navel gazing, the important part of the premise is to focus on how the characters behave in the campaign, and that the plot hooks are derived from what happens in the campaign. Having your character write letters to his family back home in podunksville in between adventures is rarely frowned upon.