In person documents:
requires being at a single location in the world
single copy
in secured storage
in a secured building
filled with people who can shoot you legally
Online documents: Can be done from anywhere in the world
infinite copies can be made easily
1 hack can un-secure the data
threatening to shoot a computer doesn't have the same impact
Its really a computer hacker versus traditional spycraft. Spycraft isn't impossible, but does require assistance and tech from nation-states, and is prone to a set of really bad negative eventualities if caught.