But, still, this isn't an argument that any of this cooperation at all requires civilization, which seems, to me, to be false prima facie, especially given all the interactions people engage in on a daily basis without using the fixed relations that civilization imposes upon us, especially with friends and lovers.

OK, but there's a difference between interpersonal interactions that we all engage in on a daily basis, and the structures that are necessary to maintain modern technology. Take diabetes, for example — how are you going to produce insulin? You'll need a lab, and you'll need the economic networks that provide raw materials for the lab, and then you'll need people working in the lab, and then people who can provide the necessities for the people working in the lab, since it seems pretty impractical to think that someone could be working as a biochemist or whatever and also producing enough food for themself and their family. And then you'll need a transport network, in order to deliver the insulin on a regular basis to all the people who depend on it, and they'll all need fridges because you can't keep it at room temperature for too long, which means electricity, which means all the economic networks needed to provide an electricity supply, not to mention the economic networks required to operate a fridge-manufacturing industry.

I keep seeing the argument saying something along the lines of “well, if civilization keeps going the way it's going, everyone will die anyway and the e.g. diabetic people will be even worse off”. Which, sure. Capitalism is going in a very dangerous direction, and technology is a fundamental part of that. But I don't see any way we can make the world any better by just rejecting “civilization”.