I don’t think that applies to Snapshot based backup apps like Time Machine, CCC and Arq.
I have never closed a database and all 3 three apps constantly back up while I’m changing things in Devonthink and other apps.
This is in line with their documentation.
From Arq…
From CCC…
The only requisite seems to be APFS, but that’s has been the default for some time now with Apple. You can’t even create encrypted HFS+ volumes any more or use HFS+ for Time Machine.