I think it is fair to argue that there is a strong correlation between criticality of data and network scale. Most small buisnesses don't need anything S3 scale, but they also don't need 24 hour uptime, and losing the most recent day of data is annoying rather than catastrophic, so they can probably get away without flushing but with daily asynchronous backups to a different machine and a 1 minute UPS to allow for safe storage in the event of a power outage.