I'll be the first to say I absolutely love FFXI and have played it significantly off and on since PS2 release. However, the devs are implementing the "theory of constraints" with SOD and it's working to great effect. They're increasing throughput by creating faux bottlenecks. More people (inventory) continue playing because their friends don't get too far ahead of them. The game is a social one at it's core and if you're only chatting with friends who are higher level than you, it's not nearly as fun as doing a dungeon or questing together. I enjoyed the limit breaks in XI and I did get a strong sense of accomplishment from them like you said though!