Distributed blockchains are useful when all of the below are fulfilled:

• Need for distributed ledger
• Peers are adversarial w.r.t. contents of transactions in the ledger
• Enough peers exist so that no group can become a majority and thus assume control
• No trusted central authority exists

Here, we have a single peer creating entries in a ledger. We can get away with a copy of the ledger and one or more trusted timestamping authorities.