Only a database or software engineer could truly appreciate the complexity of Disney's IT. I say with all sincerity that it, like WDW's logistics in general, is a marvel. Both the logistics and the IT are things I put on par with a suspension bridge. You might take it for granted if you don't understand how it works, but if you have even an inkling of what is truly going on, you can stare at in awe for hours.
I am aware this isn't a popular opinion, but Disney has managed to merge multiple incredibly complex system into one platform. The creation of anyone of these systems, (room reservation, dining reservation, ride reservation system, ticketing system, payment system, meal voucher system, etc) is amazingly more complex than most people understand. The fact that those system then integrate into each other so that the ride reservation system knows if you have park tickets, if you have resort reservations etc is truly an impressive accomplishment. The fact that it works seamlessly 99.9% is incredible.