I have been told many conflicting answers to that question.
Perhaps its that some want to safeguard locations, thinking that they can corner the market.
Perhaps EVERYONE is having a hard time finding any and locations are simply unknown.
I would like to ask the community at large, if you have found any Arch BP's lately and only the zone it was found in.
I figure that Jordi made them very rare now, and perhaps you need to be near the mist to even find some, but I can't verify this.
ANY info you can provide is welcome.