I don’t understand why a ‚background free’ approach for a theory of quantum gravity is needed (or at least enthusiastically defended by LQG fans). I agree about the relational idea and the general covariance as nice features as in GR. Also I see that space-time makes no sense before solving Einstein Equations. But I can imagine a void space-time without any mass and energy, only with a metric (which seams mathematically possible). So, whats the problem about perturbating this background placing a given mass-energy and go further with such an approach?