Official response here.
I hate “newbie traps”, but I feel better about this explanation. Basically, it is “working as intended” (the system is automated, War & Peace is flagged as an event weapon, therefore it can be in soulforge) rather than working as actually intended (which would be you can’t get any quest weapons or mastery weapons from the soulforge). Probably entangled in a way that would take too much development resources to fix.
This combined with the “you kind of have to go out of your way to fall into this trap” global chat interaction makes me feel much better than having the latter stated independently, which comes off as “your concerns aren’t valid.”
(Diamonds > Souls, however, is an intentional newbie trap and I still feel bad about that existing every time it comes up.)