Censorship resistance

Censorship resistance arises from three mutually reinforcing factors. Decentralization of the validator or miner set: the more of them and the more dispersed, the harder it is to coordinate exclusion. The permissionless nature, which lets anyone submit a transaction and become a validator. And the economic mechanism, because excluding transactions costs money, since fees are forgone and other producers will include them. The property degrades in a nuanced way: there is soft censorship, when a validator omits certain transactions but another includes them in the next block, versus hard censorship, when including them becomes impossible.

It is the underlying justification for using a public blockchain instead of a centralized database. If all you want is an immutable record controlled by a single entity, a signed database is cheaper. Censorship resistance is the real differentiator: it ensures the asset and its movements do not depend on the will of a single intermediary, which is decisive when designing infrastructure for regulated assets that must remain transferable.