One thing that hasn't been mentioned is time, confusion & disorder.
If everything is done SOP, the PM knows exactly what is going on, and what the PF will likely lead to a predictable and safe outcome.
I've been doing a lot of reading about the fighter pilot John Boyd and his OODA loop (an absolutely fascinating topic in itself PM if you want some links). The core of this loop is to create confusion in an opponent by compressing his timescale. Time is the key element causing mis-perception, confusion and defeat.
Exactly the same thing occurs close to the ground, our timescale is compressed. We no longer have the luxury of time to sort out a mistake or a system misunderstanding either
within ourselves or
between pilots. This can leads to confusing events and misunderstanding, and sometimes an accident.
If I read the preliminary report correctly, the PF applied SOP's right up to the point where the aircraft thrust levers failed to advance in response to his pushing TOGA. At that point, because the thrust levers didn't advance, the confusion, or perception of what was actually happening began diverged from reality. However, it takes time for the consequences of mismatch to become apparent, it didn't appear straight away.
It is also likely that the ATC call, PM's "positive rate" likely all reinforced the crew's perception that things were going just as they expected, just as their training had taught them. However, by the time they realised the error, that the system had not responded as expected, there was insufficient time to recover despite attempting to do so.
A question then is what is the EK SOP for hand on the thust levers? Is it SOP to press TOGA and then place back on the control column or leave it on the thrust levers? If it is, then this increases the risk that error of the thrust levers failing to advance would have been delayed. If every single time that you press TOGA, the thrust levers advance (normal takeoff & Go-Around prior to touchdown) during training and line ops, why won't it do it today? My airline doesn't train for GA from on the runway after touchdown, but our SOP for GA is hand on thrust, stiff arm of thrust , this is just an intuitive response. Pressing TOGA is icing on the cake and for some time was a cognitive effort to remember for me personally.
So to all who say that any standard manoeuvre should "just happen" put yourself in a situation where you think you are doing everything is going SOP,
but you fail to get the expected response, now, you are confused. How quickly you can resolve the confusion will determine how it ends up.
Alternatively, imagine yourself as PM, when the PF makes make one single unexpected selection or action, you now end up with confusion that takes a finite amount of time to resolve. Normally the time taken to resolve the confusion is very quick & we get away with it because we likely have previous memory of a similar scenario (experience) and we aren't close to the ground.
Everyone needs to think about how they would handle an unexpected system response by the aircraft or mistake by someone else at a time critical point, leading to your own confusion and how you will resolve that confusion. How you would communicate the resolution to the other pilot? Not so easy is it? We are all vulnerable to the unexpected at just the wrong time.
Confusion is a feature of system of our perception & the fact that we can never have a complete understanding of the world around us. There is always a mismatch between what we think is happening and what is actually happening. In aviation, we spend large sums of money to train & build aircraft & systems to make that mismatch as small as possoble. However, it is there, and sometimes it leads to an accident. Boyd demonstrated this from first principles using universal laws of maths, quantum mechanics and thermodynamics. He also demonstrated that attempts to increase our own knowledge about the state of a system can actually leads to greater confusion & disorder.
Highly recommended reading is his 1976 paper
Destruction and Creation for a much deeper explanation of how and why this process of confusion occurs.