Miniature die filer

[tonyfoale]

Marv,

I have neither used nor seen a mechanised filer, so I am here to learn.
Does a filer do anything that the various sanding machines do not? For example a belt sander with a platten and rest at right angles, or an oscillating round sander. I understand that it has a sometimes benefit over hand filing, in that you can "guarantee" orthogonal faces.
Tell me what I'm missing. Is it maybe a tool left over from an age before sanding machines became common?