This raid tier have random mechanics i.e., A6s Brawler Cannon/drill, A7s jails combo. The fact of the matter is that in a game like this there can't be 100% rng in mechanics otherwise it would be almost impossible to clear for 99% of the people. Can you imagine the ffxiv boss acts like bloodborne or dark souls series? How many ppl will complain the game is too hard? Not to discount your suggestion bit is there a successful MMO out there that does 100% rng mechanics and no memorization?