This whole discussion has stemmed from the fact you want decision making in a job's rotation, with the implication that you would have to carry out this decision every single time you do the fight. This is compounded by the fact you use Chess and fighting games as an example where decision making has consequences and you need to keep making decisions for the whole game.

However, my claim is that you cannot have such a system in a PvE environment. Every boss rotation an mechanic will get solved and there will be a 'best' way to handle it.

In theory, you could turn to RNG to make the fights more like a PvP environment, where you have to make decisions based on what the boss is doing, however, I have explained that even there, they would have to put restrictions on what the boss can do and, depending on what the boss can RNG around, it could lead to a case where you are rewarded for being lucky, which is then frustration if you are unlucky.

However, you keep saying it is possible to construct a mechanic in a fight that will require on the fly decision making. This is not something that requires pages and pages of mock-up, this isn't something that needs to be finely tuned for the sake of this discussion. It is just a mechanic where I can't pre plan what to do and go down either option A or option B, depending on who get targeted, or the shape of the AoE based on the name. Ultimately, it would be a mechanic that has no solution, a complete mess of things going on, but even then, it will still be solved and the decision making will be lost.