If you have sat through a blockchain vendor pitch and felt unconvinced, your instincts are probably calibrated correctly. Here is what the evidence says about five common deployment claims.
Claim: blockchain removes the need for trust
It removes the need to trust a single intermediary. You still trust the validator set, the oracle feeding external data, and the team holding upgrade keys. That is a different trust model, not the absence of one.
Claim: immutability guarantees data integrity
Immutability guarantees that on-chain data cannot be altered. It says nothing about whether the data was accurate when it was written. Garbage input remains garbage, permanently and verifiably so.
Claim: deployment is a one-time cost
Gas fees on public chains fluctuate significantly. During peak network congestion in 2021, a single Ethereum transaction cost over AU$200. Permissioned chains avoid gas but require dedicated validator infrastructure with ongoing maintenance costs.
Claim: smart contracts execute exactly as written
Yes, and that is the problem. The DAO hack in 2016 exploited a re-entrancy vulnerability that the code executed perfectly as written. Correctness and safety are separate properties that require separate verification processes.
Claim: decentralisation improves resilience
It can, but most enterprise deployments use three to seven validator nodes controlled by the same organisation. That is not decentralisation in any meaningful sense. It is a distributed database with extra steps.
These are not arguments against blockchain. They are arguments for deploying it with accurate expectations rather than inherited marketing language.