Aren’t these all details the player normally decides? If I was a player creating a human PC with a background in the Flaming Fist I would expect to have to answer the same questions.
And if they are just some NPC guard, then you need to know different things about them. What it’s their personality? Are they honest or corruptible? Are they perceptive or gullible? Where they live is irrelevant (but most likely in the barracks), since it’s not going to come up when the players interact with them. Again, the same questions needing answers, irrespective of species.
Missing the point.
I'm not talking about my own character. I'm talking about the connections my character has to an NPC. The NPC has zero connections to the setting because the NPC Dragonborn doesn't actually exist in the setting. I have to not only make up my character, I also have to make up the NPC and then make up any connections that NPC has to the setting. Which I can certainly do. Everyone reading this can do that.
But, at no point does any of that actually leverage anything in the setting. I can take that same NPC, file off "Member of the Flaming Fist" and replace it with, "Member of the Bronze Band" and nothing changes. Nothing in that NPC is connected to anything in Forgotten Realms. Again, sure, "make it up" is a solution.
But, again, this has been the point I keep harping on. If I make a human PC with a human connection to a member of the Flaming Fist, I have several canonical choices that I can leverage. There's a dozen or so named Flaming Fist human mercenaries, many of which have (admittedly short) biographies. If I want to be a drow, I can say I have connections to the Bregan D'aerthe and, again, I have dozens of NPC's detailed that I can choose to have connections with, and, again, just like those human Flaming Fist NPC's, they come with built in stories and connections.
But, if I make a Dragonborn or a Goliath PC and I want to have any connections to any existing factions within Baldur's Gate or Waterdeep, I have to create not only my PC, but the NPC's that I have connections to, and then make up the connections that they potentially have connections to. All of which is 100% pulled out of thin air and has nothing to actually do with canon.
What's the point of having thousands of pages of setting canon if I can't make a simple PHB fighter that has connections to the most detailed setting out there?
Look, if I want to make a reified dream of an Aboleth as my species, sure, ok, that's going to be 100% on me. But a PHB character? Heck, don't Dragonborn exist in the Basic set?
That's the advantage of actually building a setting based on the game as it exists.