That's a fair point. When I wrote "centralization" I mainly meant components rather than development model. Systemd is very "centralized" in that a single package does a lot, but Linux as a whole is very decentralized in development model. BSDs are "centralized" in the sense that they have a single tree in source control, but the main result is a rather small, very configurable base system. (Then you deal with ports and packages on top, which feels more like a Linux distro: scripts that pull distfiles from lots of different sites and apply patches; not unlike the experience of building a .deb from source.)
But I did not want to imply that "decentralization equals less choice". As an example: Android is as centralized as you can get for an open source project. That does not stop people from customizing it to bits, so much that it's barely recognizable as Android anymore. The beauty however is that people can do that without influencing the direction of the original project (although that happens to a limited and uncredited degree), or bitching and moaning about it.