When the Traveler visited the Fundament, there were worms there to grant Aurash and his/her sisters power. When the Traveler visited the Harmony, its people resorted to "dragon-wishes" to fight off the Hive. Earthbound Ahamkara didn't really show up until the Traveler was around. Think about that. Wherever the Traveler, these creatures show up and grant dark wishes with equally dark pitfalls associated with those wishes. Remember when Oryx remarks that "our gods should be ours alone"? Then when Savathun went and vivisected the "dragons" on Harmony, the text notes that "The Worm our god laughs and laughs." What if these creatures are not all one and the same, but they arise from similar conditions with similar goals? Or what if they are playing both sides to force the universe into further and faster entropy? You can find their attack on Harmony in Verses 5:3-4, "I'd Shut Them All In Cells" and "The Gift Mast".