The internet is both centralized, we need to agree on protocols, coordinate address spaces, issue domain names, and decentralized, where elements of it can survive independent of the others if they're temporarily disconnected.

The Bitcoin blockchain is an example of something that's a complete contradiction: It's a highly distributed highly centralized system. There's only one Bitcoin block chain, and everything must be recorded there for it to be valid. If, for example, Iran is cut off from the greater internet then that means you can't use Bitcoin in Iran.

BitTorrent is a much better example: There's no central authority, it's truly distributed, and highly fault tolerant. If Iran was cut off for some reason, all the Iran-hosted seeds of any content would still work.