Because the updated 7th seraph weapons can now drop as a world drop. That means when farming for the SotW gear, your chests can just give you a world drop instead of what is normally dungeon only drops. Which by the way is paid for content. At the very damn least, remove the weapons you intend to make drop from outside sources from the dungeon pool first. It's like doing runs in dungeon, and suddenly you just get a couple guns you got from the chests that you could have gotten any time running around worlds, and shooting random enemies.