Certainly you're right that a commercial application should not suffer from this defect.
However, "full disk access" is just a way of giving an application blanket permission for all volumes, instead of having to grant it access to a limited set of four locations that Apple has defined. If you go into security preferences under Privacy / Files and Folders, you'll see that Apple appears to have earmarked only four locations for individual access:
Removable volumes
Downloads folder
Documents folder
Desktop folder
