Reading all of this from a laymans perspective, it appears to be very simple, the aircraft malfunctioned.
In reading through these posts, it does not appear that anyone has been able to show any information from the manufacturer on how to respond to this malfunction. Nothing in the FCOM or training suggests that there is a procedure and/or training on how to recover from this malfunction. (such as MCAS disconnect procedure) This is coupled with the issue that I see little information from any airline that they were even aware of the feature.
The arrival crew had issues, but it is unclear how the problem affects the departure logic.
Like many other failure mechanisms, it is usually the folks with less experience that expose the weakness of a system.