> Earth has multiple governments. Most governments are highly centralized. No oxymoron.

But you wouldn't say that the governing of Earth in total is centralized (e.g., the UN (with their black helicopters/s)).

Going back to my link:

> As its name implies, decentralized systems don’t have one central owner. Instead, they use multiple central owners, each of which usually stores a copy of the resources users can access.

> A decentralized system can be just as vulnerable to crashes as a centralized one. However, it is by design more tolerant to faults. That’s because when one or more central owners or servers fail, the others can continue to provide data access to users.

* https://berty.tech/blog/decentralized-distributed-centralize...

Or Baran (1964):

> For example, type (b) in Fig. 1 shows the hierarchical structure of a set of stars connected to the form of a larger star with an additional link forming a loop. Such a network is sometimes called a "decentralized" network, because complete reliance upon a single point is not always required.

* https://www.rand.org/content/dam/rand/pubs/research_memorand...

You are confusing terms. Centralization is a noun describing a verb, centralize, which means to come towards a collective center, for example a cult. The verb, the action, has nothing to do with a philosophical concept of a total center.