But also, if you have no backups, incorrect ragged backups of only non-changing files are a _hell_ of a lot better than no backups at all.
And if you get in the habit of doing incremental backups every day, you might be lucky enough to find a non-corrupted version of a file that's a few days stale.
Eventually I realized that some backups are better than no backups at all, and prioritized getting _something_ in place to at the very least have copies of important files copied regularly to another drive somewhere.
It depends a lot on your use case.
If you're backing up a production database system that's in constant use, then the files are almost certain to change while the backup is in progress. And a backup of everything on the database server except the data probably isn't what you want!
On the other hand, if I'm backing up my personal computer, my family photos aren't getting regularly overwritten - and if the backup of my web browser cache is inconsistent? So be it.
Either way it was identical to crash recovery
Maintaining a super basic (but regularly verified) hourly incremental backup system has spared the people who use those PCs a lot of grief, plus saved me time trying to recover lost data.