the internet is decentralized, some parts are highly centralized, other parts less so, it is almost the definition of the word, because if you start from the model of star networks, how ethernet is usually structured, with switches and routers at junctions between groups of nodes, and then these LANs are connected to other LANs and then you have the high capacity trunk lines that connect most LANs together

it's precisely the strict definition of decentralized

really what it means is "without a center", like detached vs attached