Cited is a fear eliminated over 20 years ago. That problem observed by many who still kept using FAT filesystems (ie Win 95, Win ME). That technology had been obsoleted before OSes existed. The fewer and informed back then never used those "obsolete when first introduced" OSes. Instead used Windows NT.
If power is lost due to a power outage, then "not obsolete" file systems ignore an incomplete file save and restore a previous file. System recovery is automatic.
Worse are so many technically naive who insist other already saved data can be corrupted by a power off. It is not. It was not corrupted by a power off even when disk drives moved heads with motor oil. Power off does not destroy saved data. Power off is only a threat to unsaved data.
One condition that could corrupt one file during a write was eliminate by technology that was standard over a generation ago. And still that myth lives on.
UPS provides temporary and 'dirty' power so that unsaved data can be saved. And to avert an inconvenient reboot.
Nothing more.