A 1% RNG for 1 item for 8 player after a 10 mn fight and a 80% chance for 1 item for 1 player that can be done anytime is not the same, both are random but one makes an item almost unique and the other very common.
The point is, there can be RNG for an item and you can get it if you are working to get it ( Atmas are a good exemple, hard but you will get them eventually ), but mounts and mirrors are too low to be farmed while keeping your mental health and to be something you can actually farm for and still have a life outside of Eorzea.
