ok.. let me put it another way,

imagine the game is re-released next week.
then read this thread: http://forum.square-enix.com/ffxiv/t...m-I-a-bad-Tank

If it takes months to get ONE job to rank 50 but raids require you have 2-3 jobs levelled to 50 to be "a good tank" or "a good healer" or "a good dd", do you think new players will really stay around and grind for half a year or a year straight before being able to do endgame content? FFXI you could get ONE job to 75 and be -fine-. Here you can't.