There's nothing stopping people from socialising even if the server is locked. There's a significant number of people still playing on the server - far more than on some other worlds - and there's always someone online at any given time. The stagnation on servers such as Gilgamesh and Balmung isn't linked solely to the lack of new players, it's just a consequence of each server's culture. I remember when Gilgamesh was going to be the 'sister server' to Balmung yet many there decided to drive role-players away and mock them.

Role-players, incidentally, being the sort of players to play even during dry periods in between new patches. So to some extent it's a problem of the server's own design.