Not everything reads from live databases. Some marketing is sent by running batch jobs against data sitting in bigquery, hadoop, etc. So even if a write to the

Not everything reads from live databases. Some marketing is sent by running batch jobs against data sitting in bigquery, hadoop, etc. So even if a write to the source of truth happens at some time, a job running an hour later might not see that update. Also, you may have bulk sending tooling which throttles the rate at which messages get sent out, also slowing down responsiveness to an incoming request to unsubscribe.