Its even worse. In many cases blockchains still require a central authority that controls the write access to the system. A blockchain / distributed ledger can

Its even worse. In many cases blockchains still require a central authority that controls the write access to the system. A blockchain / distributed ledger can be easily flooded with spam. The only way around that is to make access expensive. That works for the "actual" blockchain because the effort to put something in the chain is the money. In applications where you don't have want expensive writes, a central gatekeeper (or at least a cabal of power-nodes) is needed to restrict access to prevent spamming.