I agree that the "love" argument was poorly stated, and framed in a stupid way (as a force, really?).

But I think it ultimately makes sense, in a Richard Dawkins' Selfish Gene kind of way. Our species has strong pro-social tendencies, where we are willing to put in huge amounts of labor, resources, and sacrifice for loved ones. In the aggregate, across large populations, that can add up to some pretty powerful emergent group behavior that adds up to something that is difficult to model through its individual components. Our species has done some amazing things, and will probably continue to do amazing things, motivated by a bunch of emotions that include what we call "love."