It comes down to a question of entropy: does it exist? Does aether move from a useble state to an unusable state? And do primals have really shitty efficiency rates?

Note: aether that's been "used" can't return to a "usable" state. If aether never moves to an unusable state, thermodynamics and entropy do not exist and, while things can be bad in the short term, there is no long-term fear to be had. Yet we're constantly reminded of how dangerous primals are to the long-term health of the planet...

If the aether used to summon a primal can be returned to land, the rest would have to be "lost" as far as usable energy goes; that's the only way I can figure that leads to the fear of primals killing the planet making sense. They're entropy engines.