Nostr is actually much more centralized than legacy platforms, in practice, as there is no mitigating effect to counter the name recognition some npubs have when they arrive here, and so many people are only here to read what some particular person or persons writes. It's mostly a collection of fan clubs.

Discoverability of material is an effect of overt human reactions, so that creates a permanent vacuum to the same handful of npubs, as they have fan clubs who react as a sort of homage ritual.