Hackers manipulating data rather than selling stolen data (as is) is something that needs to be looked at more seriously. https://qz.com/1130434/the-dangerous-data-hack-that-you-wont-even-notice/ I have my doubts that Corporations and Government have the wherewithal to implement this foil.
Preventing exfiltration of sensitive docs by flooding systems with hard-to-detect fakes https://www.helpnetsecurity.com/2018/09/14/preventing-exfiltration/