Using this standard, what is decentralized? I'm not convinced that either end of the spectrum actually exists in reality or even can exist. You start getting into philosophy the deeper you dig, but even the most centralized systems aren't entirely centralized. Consider Twitter. Yes, that's pretty centralized, but Twitter doesn't own the ISPs required for it to exist, etc. Something like BitTorrent is pretty decentralized, but the peers are still owned by people who can therefore have some control over it. Someone still has to seed things on controlled hardware for it to matter. And the networks for transmission must exist (internet, etc).

I think the important thing that tips the scale toward decentralization is the ABILITY to run your own relay, not necessarily that people choose to. I just fundamentally disagree that decentralization means no centralization, at least outside the realm of philosophy or theory. It's just farther from the centralized end of the spectrum. I believe this is why massive regimes always fail as they try to reach peak centralization. On the other end, some things tend to centralize for efficiency. I think Nostr will have the same pendulum like cycles. Obviously, we should try to be more decentralized where we can and when it makes sense.

What would you use to transmit notes that absolutely no one can have any influence over? Because that's what you'd need to have zero centralization as far as I can tell.