Every newspaper in the world uses microfilm as its primary backup --- and you can go to any newspaper and request a copy of a printing from 100 years ago.
The biggest concern about Databases is that they can crash. However, paper takes up huge store rooms, time and resources to create, and as far as organization is hard to keep track of (without an electronic database that is). Even if an agency possesses a hardcopy file, there is no guarantee that they will be able to locate it.
Microfilm is inexpensive, as reliable as paper and as manageable as a database. And it has been trusted by all the major newspapers in the world for nearly a century.