SE thought people would play nice, and help each other all time. Join together to help your fellow player through story line dungeons.

BUT, since there is no reward for them, they just don't care.

There is no reason for someone to do dungeons once they complete the story because Fate grinding is how everyone levels there alts, it was expected that people would level alts through dungeons so in the end it shouldn't be a problem. Also the dungeon finder originally was suppose to choose from all servers, but it was crashing the game by doing that, so they had to break the servers up into 3 or 4 groups, so there is also now less people to choose from.