Why are duties insane hard?

[Felis]

This would be reduced if there were stronger tutorials, but the game kind of just expects players to intuitively know what to do, which clearly doesn't always work.

Most of the mechanics were already in previous contents.

And "dodge AoE, kill adds fast" is standard knowledge

[Hundred]

Most of the mechanics were already in previous contents.

And "dodge AoE, kill adds fast" is standard knowledge

Mechanics are explained, via guild hests and well prelimary dungeons/trials.
Their flowchart for skill use isn't, hence a lot of poop damage
Tanks whom can't rotate a target, most people don't even know there is an enmity bar in the party list.

A lot of the time mechanics aren't the issue and failing on mechanics themselves is particularly minor since those are learned naturally (unless you watch a guild) by bopping your head on them. Handling tank busters is in the same vein as encounters have different frequencies of attacks.
If a person however hasn't learned how to deal out their damage...then there is a problem. I did a quick look through active help.
Use combos to deal damage. Learn when to use Astral Fire & Ice. Thats basically what it tells them. The latter expects them to piece together the puzzle based on the explanation of the mechanic. Unfortunately something to consider this is all put at the initial stages. What you're doing @ 50, @ 60 isn't necessarily the exact thing you did at level 5, you have dozens of additional skills. Should you be leading with Thunder 3, 2, 1, or not at all? That's not explained to them. Does Phlebotimize take priority over your chaos thrust combo? Not explained. Unfortunately the finer details as players gain new skills are not explained for how players should then incorporate these skills.

Intuitive players take this up, or study their options and figure it out. Other players look it up. Then there are players whom are not intuitive and don't look things up. They're fully capable of doing their job, but they don't know how to do the job and the resources that explain things to them are based on the initial skills of the first 10 levels the majority of the time.
While most of this might seem "obvious" how to use, it's become rather clear to me that it isn't and that many players do not look for guides when they are lost.