Its interesting that this article focuses on the access to the partnership's data when I think the bigger risk is really the complete destruction of said data. I guess lack of access is effectively a form of destruction.
Storing your data online whether in your office or using some magic "cloud" service presents different risks to ye-olden-day paper files.
If her business had only maintained the single set of files in paper form she may have had a much bigger problem - her mischievous partner could well have destroyed all her files simply by burning or shredding, or even just carrying them away. Presumably if she trusted him with online access to their electronic files she would've trusted him with a physical lock & key.
On the other hand its much faster to destroy electronic files than to burn or shred several kilos worth of paper. But offsetting that its also much easier, and cheaper, to make multiple copies of electronic files than to photocopy thousands of sheets of paper.
I like the final paragraph:
Maybe the thing to do in this digital age is to forgo dramatic exits and weekend benders as responses to domestic or professional disagreements and instead (after you're done shouting and slamming doors) make a backup copy of anything you might want to have on hand if the relationship goes sour?
I try not to maintain paper files any more, choosing instead to invest (money and time) into my (electronic) backup strategy, and scan most of my important (i.e. tax relevant) documents.