Can we add a motivation section to make it really quick to see what this is and what this isn't and what it solves?
Afaik, it doesn't put files into relays, so it still has the risk of files going missing... I'll keep reading now.
Discussion
no, it doesn't *necessarily* put files into relays, the relays have to implement it
it does implement a method for regular CDN type hosting to be the target for a content link but also allows for relays to do the same thing