Earlier quoted context omitted.
That doesn't get away from the issue of payment, it just moves it around. I think it does so in a way with a lot of positives, but there's the whole P2P bootstrapping problem in the way, both in terms of creating the code that even works and then actually bringing the network online, and unfortunately it seems that's a pretty big negative in practice.
It just "moves it around" to the point where the cost is so spread out as to be effectively zero. What's the average cost of a volunteer-run peer to peer file sharing network?
You can only talk about the "all but 0" marginal cost when you can produce a piece of software that really does have an all-but-0 marginal cost. And, therefore, doesn't require the computer running it to be always on, or run on a dedicated VM, etc. Sure, such a thing may be possible, but you have to produce it first.
Unfortunately.