A brief explanation as to why they did it.

https://www.youtube.com/watch?v=EDYBssWnlwM

As a side note, I worked in IT. Major banks would have dedicated storage and backup teams to prevent unwanted deletion of documents. They typically store these files for many years. There is no such thing as "mistakenly" deleting records beyond the ability to recover them

A brief explanation as to why they did it.

https://www.youtube.com/watch?v=EDYBssWnlwM

Would be a shame if someone kept a backup...somewhere...