FFXI's partying system, whether the developers planned for it or not, was dynamic and diverse.
What's so dynamic and diverse about sitting in town waiting until a RDM or a BRD and a PLD or NIN logged on and wasn't snapped up within 15 seconds by other desperate groups? There were levels when you couldn't even sub Dispel and without it, there would be no practical way of doing any form of decent experience on Robber Crab/Crawler Tedious Grindfest Mania when dealing with people with attention spans shorter than their vocabulary and bladders the size of peas (just how difficult can it be to synchronise a toilet break?).