Metcalfe's Law [0] dictates that the value of a network service scales exponentially with its number of nodes. This tilts the table in favor of winner-take-all ecosystems; moreover, in terms of both political soft power and cultural influence, this often creates a pressure for users to participate, not quite under duress, but let's say unenthusiastically, lest they be left out of the conversation.
[0] https://en.wikipedia.org/wiki/Metcalfe%27s_law