I'm not sure that this is true, that you really need density, because density is not the way humans interact. We interact with networks of social contacts, now

I'm not sure that this is true, that you really need density, because density is not the way humans interact. We interact with networks of social contacts, now if you virtualize contacts or if you have a higher network density, that means less people but they are better connected you might be able to compensate a lower overall density.