I understand that the difficulty is relative, because not alll people have the same capabilities, but if you are trying to make discipline somehow make up for people who are really bad performance wise, you will probably have a problem. And trying to use such situation and logs to make points is probably going to give you scewed results.
The mechanics do not change, the amount of mistakes does, and the ratio of spot healing - unavoidable dmg healing. If you start optimising for a case with mistakes etc, dont you need different optimisation for each circumstance? Each raid group will get its own analysis and conclusion? Also would you say that the popular burst gameplay simply will not work in any case?
You can try to do that 110% to help your friend who is doing only 30% for some reason, but that would be a combined product of your personal familiarity with their weaknesses and your proper knowledge of the spec, and certainly not a good basis for conclusions. You want a starting point. Then you shift the context to a more chaotic one and adapt. You begin with a basic but refined plan. If you start on the premise of mistake, you do not plan to deal with the original problem, but a circumstance. and your solution will almost NEVER be right for others, because no two raids are the same. Noone can really do this adaptation properly but you. Whats even the point of asking theorycrafters how to deal with a raid that falls on its sword and dies?
Now people who struggle on heroic or even normal, on fear of sounding arrogant myself, at this point of the franchise, probably fail at the base boss mechanics miserably, and are a different type of help is needed. You can play however you want and still beat the boss, no optimisation needed, apart from pain suppping that fool, and knowing when to spam smend to keep them alive.
Could you give me an exaple of disci optimisation in your opinion for a group with difficulties, apart from shadow mend emergency life saving since we all agree on that? I would like to see a solid example of said case.
In my opinion, its not that there was no proper answer given for those facing problems in the lower difficulties, but rather that the same strategy will apply, only the REAL problem is the people themselves, and the REAL solution is them improving. Shifting the need for a solution to the disc priest is an exceptionally bad move. Anyone wanting to trully help his raid will help his co raiders deal with basic issues first. The so called "Git Gud", is the hardest step of the learning process no matter how much it hurts ones ego.