From my understanding: It existed, and the German apparatus acted as if it did. Turning Madagascar into a SS-run concentration camp as planned would have been genocide too, so it arguably doesn't matter all that much. Similar to some of the other "Jewish reservations" that had happened previously, e.g. Lublin-Nisko: It turns out if you cram many thousands people into an area without infrastructure, shoot everyone who tries to leave and add some forced labor, survival rates are not good. Who at what point considered mass deaths to be the point of the exercise vs just a (tolerable or welcomed) side-effect boils down to an aspect of the functionalism/intentionalism debate.