Actual crash investigations don't work that simplistically. It's not about being able to assign blame to one single factor. It's about understanding how all of the pieces fit together to cause an airplane to fall out of the sky.

So, it is undeniably true that Boeing rushed an aircraft into development that crashes very easily under certain circumstances - but Boeing did not create those circumstances, nor did they expect pilots to be unable to deal with them if they arose. Boeing wasn't flying either of these planes when they crashed. MCAS is what I like to call a "resident pathogen" - it paves the way for an accident to happen, and the accident can't happen without it...but it alone cannot cause an accident.

What you tend to do in an analysis is work backwards: what did the pilots and ground crew do that was unsafe or violating safety protocols? In the case of Lion Air, they installed a refurbished AoA sensor that hadn't been calibrated using standard practices, and the results were not documented. The flight crew of the first flight to see erroneous MCAS activations didn't log the errors properly. And the flight crew of the crash flight didn't declare a state of emergency, and had personnel issues that prevented diagnosis of the problem.

In the case of Ethiopian Airlines, we are now pretty sure that the AoA sensor antenna was hit by a bird strike during takeoff. And while the pilot did diagnose the problem correctly and turn MCAS off (and the telemetry does tell us that MCAS tried to send a command to the stabilizer and it was disregarded by the flight computer), he didn't follow the procedure of turning off the auto-throttle, and this caused the flight computer to disregard the auto-throttle's commands to throttle down the engine.

Once you've identified those, you turn to the "resident pathogens." Why were these actions able to cause a crash? Well, you have MCAS and the problems it creates. You have the fact that there is a known problem with 737 airframes that causes the stabilizer to lock up when the aircraft is in mistrim as soon as the electric trim is turned off, and the procedure for resolving this was removed from the manual sometime in the 1980s. You have Boeing having promised a seven-digit rebate per plane if the MAX required additional simulator training, giving them a reason to avoid it at all costs. You have the whistleblower from Ethiopian Airlines bringing to light that maintenance was being signed off on without having been completed, and those who complained were being detained and even tortured. You have the fact that the airport Ethiopian Airlines 302 took off from is located next to a nature preserve, increasing the probability of bird strikes on the runway (and there's even a cover-up on the Ethiopian side where they throw as much shade as they can on Boeing). This is not a comprehensive list, by the way.

The 737 MAX 8 crashes are is a famous example, but they are representative of airplane crashes and how they need to be analyzed. Boeing got spooked into abandoning its plans to create a brand new airplane by one of their biggest customers demanding an answer to the new Airbus and threatening to switch, and as a result they rushed development and made an aircraft that crashes very easily under certain conditions. Other factors, most of which Boeing had no control over whatsoever, created these conditions - without them, no crashes take place no matter what flaws MCAS has. It's complicated - yes, corporate greed and short-sightedness was involved. But Boeing also honestly thought that a properly trained pilot could save the plane if MCAS did an erroneous activation, and they ignored all the evidence to the contrary in their selection bias.

So, it's complicated.