In response to the OP, I don't consider myself a hardcore player at all, but I think even as a "casual player", you should at least try to learn whatever classes you play most frequently, especially in endgame content. I shouldn't need to tell tanks in Expert Roulettes to turn on tank stance, for example, or remind a White Mage in a Seat of Sacrifice party to use their Lilies. This isn't putting someone down for "not getting gud", this is just asking people to understand how to play the classes they choose to in endgame content as a courtesy to their party members.