Sure, but ultrapeers/supernodes/routers/etc are forms of centralization. Locally, the network is centralized around these supernodes, and they can be annoying/i

Sure, but ultrapeers/supernodes/routers/etc are forms of centralization. Locally, the network is centralized around these supernodes, and they can be annoying/impossible to bypass. The "inner network" or backbone of supernodes, if exists, can also represent a central authority. Nothing necessarily wrong with any of this, but it can stretch the meaning of P2P if it really means P2central-authority2P. Functionally there is almost no difference between me sending you an (anonymous, encrypted) message over Facebook versus over some sophisticated, large, hierarchical "P2P" network. We still have to trust the local authorities, so to speak.