I am interested on your opinion on a simple scenario I will list below.
If we go by an encounter has a minimum required performance set out by the devs, then that means the fight will be cleared if everyone performs to this minimum standard. However, what about when you have a group that can still clear the encounter, there are no deaths, however, one of the DPS is performing at under 10% of their potential. This means the other players are having to make up for the DPS deficit of this one player.
My question is, despite, as a group, the party as a whole is meeting the 'minimum required level', one player is massively underperforming. Would it be fair to say this player is NOT performing to the minimum required performance which means the others have to perform to a higher standard? If so, why is it fine for that one player to put less work into clearing the fight than the rest of the party? They could replace that member with someone else and clear the boss quicker, which means less time for mistakes to happen, less time for resources to drain etc.
Basically, what this boils down to, SE has a set expectation, a minimum performance level that needs to be met. So, how do you measure it? If you keep hitting enrage with no mechanic failures and no deaths, however everyone in your group thinks they are doing fine for their rotation, how can you find where your weak spot is. You cannot just say, play better, they already think they are playing at their best and this is where the issue lies with alot of people.
People go into content that they are not ready for, however there is no way ingame to tell if someone is ready or not, this is why people then turn to parsers. Even with a new fight, an experienced player can still output a respectable level of DPS, so if you have someone who is clearly underperforming from the get go, you can either say they need to get better or you replace them.
Even if you do a personal one, you still fail a check and someone asks how everyone done. Are you going to be the one who says, yup, the game tells me I'm the one who is doing badly, or are you going to stay silent or lie?
Again it comes down to the minimum expectation and the game does not give any feedback to say yes, you are good enough or no, you need to get better. A minimum performance line has been set, however, you don't know if you have crossed it yet.