When they were relevant? No way.
Bismark required a modicum of coordination, and upon its release, the DPS checks were mildly difficult.
Ravana actually has mechanics that are somewhat complicated (i.e. prey, swords and following divebombs).
Garuda also required coordination with regard to adds, dodging slipstreams, and actually being cognizant of the spiny plume.
I am of the opinion that Ifrit was always one of the easiest extreme primals, but I did the fight on DPS when it was current content, so I didn't really have to worry about searing wind.
The big difference between the extremes and RM, in my opinion, is how ridiculously forgiving RM is. You can have two to three people dead at all times and still clear the fight with little difficulty. As far as I know, there are no DPS checks, the healing is trivially easy, and none of the mechanics are new. Not to mention, failing any given mechanic doesn't usually result in death.
Sure, RM is harder than the absolute faceroll nonsense that unsynced primals are nowadays...but that isn't a good metric.