The key factor here is the unspoken suggestion that AFK leechers are all RMTs, whereas everyone earns Cruor (ie. Gil) magically while only one person actually "earns it." This dynamic is what throws economic principles out the window, because gil (money) is being artificially generated and injected directly into the economy.
Unlike in the real world, where systematic checks are in place to control the injection of "new money" into circulation, this does not exist in FFXI. The question becomes "which system is better?"
The system where Gil is hard to come by and uber gear is expensive, or
the system where Gil is easy to come by, and uber gear is proportionally more expensive?