too many variables to consider
job boost,higher level job unlocks like SGE and GNB,disabilities or just unawareness,
can't really have any expectations when the game doesn't set any in the first place, I've seen shire weapons in ShB content,I've had 3 warriors this week all have berserk in 80-90 content,have stood around for 5 minutes in e7n waiting for one of the tanks to turn on their stance so we could start and both just did nothing waiting for other to turn stance on.

in a multiplayer game as big as XIV its just how it is.