MCAS in itself doesn't seem to have been the problem. The fact that MCAS relied on a single sensor (no idea how that got certified in the first place) and that pilot were not aware of MCAS and how it worked were the problems. The latter was due to Boeing trying to avoid re-training and re-certification of air crew.

> pilot were not aware of MCAS and how it worked were the problems

If the pilots followed runaway trim procedure, which is how the MCAS failure manifested, they would have been fine. In fact, that's what the other unmentioned crew of a 737MAX did that survived MCAS malfunction and landed without incident.

Boeing issued an Emergency Airworthiness Directive about the procedure, which the Egyptian Air pilots didn't follow, either.

I thought there were some conditions in which manually adjusting trim became physically impossible (or at least extremely difficult).

If the wheels fall off your car, is the problem with the purpose or concept of wheels, or is the problem with weak axles?

Errr... I never said anything at all was wrong with MCAS.