Another possibility (or rather, an extension on the idea of punishment) is that it's a form of irreversible social segregation. For better? as in: "we, the enli

Another possibility (or rather, an extension on the idea of punishment) is that it's a form of irreversible social segregation. For better? as in: "we, the enlightened and courageous fingerless!", or, more likely-seeming, for worse - as in: "the shame of the fingerless shall be forever visible to all".