One can approach it with a reality comparison. But there's the problem, since too many people in this game have zero concept what reality bears, and how it works..
But for the approach..
Let's be generous and compare the task of a raider, with the task of an employee at work. Let's for the sake of it compare the raid leader with a supervisor/dept manager.
In reailty: When an employee makes mistakes, it's the supervisors/managers job to make the employee aware of it, and to ensure the employee won't repeat the mistake again. And now, much like in the game, there are all kinds of supervisors and managers out there. Some approach their position like a dictator. Bossing everyone around, calling people out for the slightest mistake, or calling them names, and what not.
Few employees fear them.. Almost all dislike them.. And almost none has any kind of respect for them. In fact, when it would count and matters, and the employee has a chance, he will leave the supervisor/manager stand there alone in the rain of a difficult situation. Why would you help someone, why would you go the extra mile for someone who otherwise treats you like shit with very little respect or any at all for you?
Modern management handling knows of this. Managers and Supervisors are actually trained (in good companies) to properly interact with the people assigned to them. The most productive people are those who do their job happy. And the most successful and productive departments are those with a leader which is respected and liked by his/her team. And how do you get that respect and "love"? You earn it by treating your people with respect, kindness and skill.
Now where can that be transported into the game?
By the fact that after all, raiders are people too. Humans, and with that the simple psychology that applies to IRL matters, also applies to ingame matters.
From there.. if there's a problem with a players performance, then do some 1 on 1 counseling. Get to the root of the problem with the player in question. Help them to improve, by finding out why they are not up to par and give them pointers and support.
If you treat them like shit, to the point where they'd get a emotional breakdown, you are crossing a line right there..