I'll provide some current history on this server seeing as how I've been here for about half a year. When I came it wasn't big but still active and people were generally glad to see new people especially FC's.
An issue is keeping serious progression players here because of the influx of casual players who aren't concerned with endgame content. If you are into raiding and progression you may struggle to put together a team unless you have a surplus of friends or find players with the same schedules and mindsets. Most of the endgame progression is done by an amalgam of people from various FC's who come together to complete it.
Mateus is Notoriously populated with large non-progression Social FC's which is why Mor Dhona may seem like a Ghost-Town. Despite this FC's are very tight-knit and tend to stay to themselves unless a certain agenda forces a few players to search for others beyond their FC for help. Also the Party Finder is Abysmal for that very reason.
The upside is that because it's a small server there is hardly any drama or issues with things like Hunts or getting into Gold Saucer everyone pretty much gets along. Mateus isn't new it has a fleeting player base which I hope resolves itself with the expansion & overpopulation of other servers.