Orci is claiming that he wishes to leave behind the past for a more realistic fiction in which there are no GRANDFATHER PARADOXES. He wants a more realistic Trek. Connecting old Trek to new via the overlap of universes and the causal connection of people hopping from one universe to another undermines this avowed intention. A hard reboot does not necessarily mean a more realistic universe. A soft reboot, however, involves swirling an unrealistic old universe into your new universe.