Meaning there is a single source of truth. That single source is decentralized (because blockchain), but it still requires a quorum to agree to accept a bit of data, and to treat the new state as the valid state. I.e., multiple competing parallel writes must be serialized across a network of computers, which is always more expensive than if they multiple competing parallel writes can be done in parallel.
Lamport clocks and etc are AP. It fully expects nodes to make decisions autonomously, and to synchronize after the fact. And data can be lost without realizing it.
(The above is all a bit of a simplification, but fundamentally, they're solving different problems)