I'm still baffled ...
I don't think we care, but it's a bit mad that it works like this.
I've always seen a Quest as the Container of Variables (aliases, whatever) ... but if you can "fill" items in that Quest, when the Quest isn't even running (and/or has never run) ... well then it's no wonder persistance drives us all up the wall.
It seems it is not really supposed to work this way ... given the issue experienced on the NPCs that are filled before the quest is started (and they would have to be forced, I assume, or there's even less I understand!) ... so something behind the scenes isn't quite working the way we thought it worked from the "documentation" (note the quotes

)