This is taking the loresplanation just a little too far; of course there isn't someone collecting aetheryte maintenance fees from travelers as they arrive at Ultima Thule--and we're probably not even Teleporting to Ultima Thule as far as the game universe is concerned. But the game is the game and we need aetherytes in places where there maybe shouldn't be aetherytes just because we have a certain expectation of convenience that new zones need to uphold because nobody wants to teleport to the place where we began the journey to Ultima Thule, fly into the place with the thing, and then get on to the thing, every single time they want to go there--if it even is far enough in the story that the thing is not just assumed to still be at Ultima Thule.