A problem I've been identifying lately are these people coming in from duty roulette with endgame builds and ending up in low-level dungeons they've done maybe 1-2 times, and no clue that their job uses different strategies and rotations at lower levels than what they have gotten used to as standard when spamming WP/AK speedruns or repeating other endgame content ad nauseum. Then they end up in these dungeons with undergeared players or newbies and use inefficient combos, don't know certain things about the dungeon or mechanics they could explain, and are actually more of a hindrance than help to those others. They don't realize that tanks have less enmity options, healers have less healing options, and dps are generally very limited in their overall options.

On a related note, yes, a lot of players are actually worse at the game for having FATE-grinded their way up quickly instead of having done every dungeon about 5 times for their job to really get practice with it on all levels.