What do you mean by "decentralized"? Do you mean someone can add a third-party repository and download packages from there? (Then it's been the case for other environments too)
I think decentralized is meant as "there's no central repository" here.
There are two different meanings of 'central' in play here, 'center' as in a town square, and 'center' as in the centralized component of a system.
It does not imply that there is a central repository when using 'central' to mean 'a unique, difficult to replicate, or otherwise somehow special component in a system' as in 'centralization'.
Central in the case of 'Maven Central' means something closer to 'default' or 'town square' or such.
Saying that 'maven central' implies maven isn't decentralized would be the same as saying "Most go projects are on github, so go can't be hosted in a decentralized way because github is 'golang central'".
> Saying that 'maven central' implies maven isn't decentralized would be the same as saying "Most go projects are on github, so go can't be hosted in a decentralized way because github is 'golang central'".
It's not, though. Because github isn't the default. You have to explicitly specify that you want a project from github every time you use it.
The difference might be minor from a technological standpoint, but it means a lot in terms of how centralized things become culturally.
I think decentralized is meant as "there's no central repository" here.