Everything is the fault of the game. They control what kind of community they will attract by setting the stage with the game mechanics.

The leveling speed, the amount of teamwork and communication required to accomplish things, the personal involvement necessary with the battle system, the pace of battles and the battle system, the level of involvement people need in the community on their own server, the types of systems available for player community organization, the balance between different types of content (endgame, leveling up, story, crafting, battle, etc.)...all of these things are set by the development team. In XIV's case specifically, with regard to the OP, they chose to make FATEs what they are, they chose to have the "duty finder" system, and they chose to make it possible to get to endgame in three days and then spam dungeons for tokens.

Player populations are essentially completely predictable given what they are allowed to do in a game. The features and content of a game attract certain types of people and don't attract others. It is not a coincidence that WoW's community is the way it is, or FFXI's, or EVE's, or anything else.