There have been some interesting observations in the gliding world, showing that a small proportion of people learning to fly are very sensitive to reduced or negative g and associate it with falling (stalling), giving an instinctive reaction to push their hands out in front of them to cushion the fall, so the theory goes. As they are holding the stick, this reduces the g even more, leading to more sensation, pushing, etc.
There have been quite a few unexplained dives into the ground in aircraft that have been found to have been serviceable pre-impact. I’ve been witness to two.
It is possible that someone could train as a commercial pilot without being exposed to this kind of scenario, especially in IMC. I’m not saying this is what happened in many of these crashes, just putting it forward for consideration...