Half baked comment but I feel like many of these efforts are too purist. Sure they need to think more carefully about incentives from a systemic angle but also why not accept a hybrid design that doesn't depend on those in the first place? For example plenty of people operate their own nameservers for their own websites to use, or spin up a VPS to support [thing] they make use of. So at a minimum I'm sure webring-style infra where you cover for your friends and they cover for you would work quite well.

For a real world example of a hybrid approach that works see bittorrent where torrents can optionally contain urls that point to alternate download sources in order to speed up the initial seeding phase.