Consider each program as a node in a graph, with the edges as the possibility of interop -- output of program A working as input of program B. With UNIXy comman

Consider each program as a node in a graph, with the edges as the possibility of interop -- output of program A working as input of program B. With UNIXy command line programs this is pretty close to a fully-connected graph. So, per Metcalfe's Law, the value scales with the square of the number of programs you know how to tape together. Command line programs compose like this, GUIs don't.