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Wow, that is an astonishing article. Of note:

"Boeing said...that the stall-prevention system is not mentioned to pilots in the aircraft flight manual because it didn’t think pilots would fly the plane in such a way that the automatic system would ever take over..."
Pilots for American Airlines and Southwest were told MCAS was installed “to enhance pitch characteristics during steep turns with elevated load factors and during flaps up flight at airspeeds approaching stall.” Southwest also told its MAX pilots that in theory, they would never see the system kick in. "Since it operates in situations where the aircraft is under relatively high g load and near stall, a pilot should never see the operation of MCAS."

I started up power plants for a living and never once did we even THINK about telling the operators we were training that "you don't need to know about this system because we don't think you will ever operate the plant in a way that this system will ever take over."

Here is the DFDR data from the investigation (PDF file), unfortunately the narrative is not in English, but the data graphs are labeled in English.

http://avherald.com/files/lionair_b38m_pk-lqp_jakarta_181029_knkt_data.pdf

Yes, agreed. The fact that Boeing released an emergency airworthiness directive that advises crews of potential problems with MCAS is testimony to how important this previously unknown (to pilots) safety enhancement is, and a tacit admission that it played a role in the Lionair crash.

After Air France 449 crashed in 2009 the aircraft manufacturers sought new ways to prevent losses of control of aircraft in flight. So did the operators, through simulator training of stall recovery recognition and techniques.

The 737 Max is the latest iteration of the workhorse 737 fleet (certified in 2017, first deliveries in 2017). It’s the first generation of the 737 to have MCAS.

In this case the enhancement actually contributed to a loss of control, to at least some degree because the crew was not aware of the stall prevention system characteristics.

There was a really good article in Popular Mechanics about Air France 447, well written but without too much technical jargon: