The current shape of the internet itself (BGP peering among autonomous systems, a decent number of large tier 1 ISPs, etc) is, on its face, a relatively success

The current shape of the internet itself (BGP peering among autonomous systems, a decent number of large tier 1 ISPs, etc) is, on its face, a relatively successful federation. The applications running atop that federation are, as you say, centralized, but much of that is because residential ISPs forbid customers forbid servers and even if they didn’t (they haven’t always) residential customers are prone to accidentally running botnets of various types.