[bravetraveler]

Totally, it's certifiably untrue!

Take the InnoDB storage engine in MySQL/MariaDB for example.

For performance (and likely other) reasons, this file only grows. It never shrinks... it will only go to 0 or grow.

The DB (or individual tables, depending on config) have to be truncated/emptied to reclaim those blocks.

Stop it uncleanly and there's a good chance you'll have to sacrifice a considerable amount of the data just to get the engine to start

This and countless other things have to make consistency trade-offs. While everything could be written to only operate atomically, it will also slow to a crawl.