I think that's a popular way of thinking because people like the word 'diversity,' not necessarily because it makes any sense. If you wanted to write the next Digg, say, would you hire a chemist, a programmer, and a doctor? Or would you hire three programmers? Would you hire programmers that use different languages or three who use the same language?

In practice, you get so much accidental diversity between any two intelligent individuals (we are all quite different) that its rare that you have to go looking for more. Diversity is the great good and ideal of our time, but a rather flimsy idea when you get right down to it.