that only applies if you use a home (single) PC. in a network of PCs you can put a file in a shared folder when the need for that file arises (editing/post editing, printing), especially when economics plays an important role in that network. meaning you don't anymore purchase a usb thumb drive or a rwcd writer and only one or two printers are present.
anyways, you can always take the file outside of the shared folder and store it somewhere you think is safe.
it's a case to case basis.