Exactly. This is no fundamentally different than a traditional time-stamping service. If the time-stamping service is compromised, all of the previous timestamp

Exactly. This is no fundamentally different than a traditional time-stamping service. If the time-stamping service is compromised, all of the previous timestamps are invalid. The only alternative to a blockchain is to publish the latest hash widely in a verifiable place such as in a well-known newspaper.