In-Game Parser.

[Zeful]

We can argue semantics if you want but for every DPS class out there, there exists a rotation. Said rotation though can barely ever be followed as you mentioned due to fight mechanics which means that now once your opener's done, the priority system kicks in. What people are asking is for people to know what said rotation is so that they can better adapt in actual, non-dummy DPS scenarios and then can properly manage their class's priority system. If people can't be bothered to learn that, then they probably can't be bothered to learn a fight's mechanic which just creates a bad domino effect.

This paragraph quite clearly shows why implementing a parser is not worth Yoshi's time. The rotation exists, but it's existence has no real impact on endgame fights due to mechanics; which makes the argument that a player must learn it blindly (and make no bones about it that's exactly what you are advocating, as your reasoning for learning it can be summed up as "for it's own sake") actively harmful to a player's performance because there's no context as to why. Even in your post you fail to point out why the concept of the rotation even exists within the context of the fight.

It's easy though. The rotation shows how a Job's abilities synergize, and how each one affects the other positively to use the whole potential the class provides. It's a concrete example of the value of each move.

The endstate behind the parser is being able to better oneself as a player, not to attain perfection. As such, this answer your second question. People should carry their own weight, not drag down a group and a parser helps tremendously in that department.

And how much "betterment" is enough to have succeeded? No, "betterment" cannot be the end-goal of adding a parser, as that only has meaning in the transition. While perfection is unreasonable to expect, it is a fully formed idea that has concrete meaning within the context of the game and the raiding player base's expectation therein.

What about the other elements of social engineering? Adding a parser is all well and good, but you'll find that it'll have little effect if there's no reason to use it. So why not add reward mechanisms for actual excellence. Take the upgrade items like Oil of Time/Carboncoat out of the loot tables for all new content and only reward them to players that achieve performance milestones. There's now a connection between your performance and your progression.