Why Would a Non-Deterministic Hash Function Be Disastrous for a Blockchain?

A non-deterministic hash function would be disastrous because it would break the core consensus mechanism of the blockchain. If the same input data (e.g. a block of transactions) produced different hash outputs for different nodes, nodes would never agree on the correct Merkle Root or block hash.

This would lead to constant chain splits, preventing the network from reaching consensus and making it impossible to verify the integrity of the ledger. Determinism is non-negotiable for a public, distributed ledger.