Page "Metcalfe's law" Paragraph 5

In addition to the difficulty of quantifying the " value " of a network, the mathematical justification for Metcalfe's law measures only the potential number of contacts, i. e., the technological side of a network.

However the social utility of a network depends upon the number of nodes in contact.

If there are language barriers or other reasons why large parts of a network are not in contact with other parts, the effect may be smaller.