Your first sentence is:

> A merkle tree IS A ZK PROOF.

Later you write:

> …but they totally do prove a statement without revealing all the knowledge.

A zero-knowledge proof reveals _no information_ except that the statement is true.  This is not a property that merkle trees have. Many proofs don’t reveal all the knowledge. E.g., ECDSA signatures don’t reveal the private key, and yet they prove that you are in possession of it.

So no, merkle trees are not ZK proofs, and it’s just false to claim that they are.

> Cryptographers often consider things like merkle trees or signatures not ZK proofs but to be categories on their own ... but they totally do prove a statement without revealing all the knowledge.

tomlaies

No, merkle trees are not zero-knowledge proofs.