I still think back on pre-nerf "The Steps of Faith". It was a fun fight that had a heavy focus on the team performing the mechanics or else they would lose.
The result? Waves of people complaining over how the trial was too hard, to some even impossible. That it was gatekeeping them from entering the new expansion (HW) so SE nerfed it.
Same thing with the quest "In from the Cold". Maybe it wasn't mechanics like in dungeons, but it required people to perform tasks to progress while the player had to pay more attention during encounters due to the shift in character power.
When players come across encounters during "casual" enviroments and it proves too much of a challenge compared to how it usually is, instead of taking the time to learn and improve as a player a lot complain over said difficulty and it gets nerfed.
Casual players in FFXIV (not all ofc) doesn't seem to care much about putting the effort into personal improvement but rather to just be able to get through the story without putting too much effort into it.