if Larian want to define an origin character in BG3 as any character we can play that has a predefined story that we can discover then that's okay by me
Well, if Larian defined Origin Characters that way, then that would be ok by me too. But, both in their FAQ and the Community Update #21, they explicitly defined Origin Characters as characters that you can recruit as Companions, if you don't play as them.
I don't think we know enough to claim the Dark Urge isn't an origin character, although you are welcome to your opinion and to speculate.
What we know for certain is the definition of an Origin Character.
On top of that, as I remember it, Swen/someone at Larian explained during PFH 8 that the Dark Urge was exclusive to a Custom Player Character. If the player does not select Dark Urge at character creation, there is no Dark Urge in the campaign.
If it turns out, once the game release, that players who didn't play as Dark Urge get to encounter them, and can recruit them to their party, I'll happily update my opinion.
