Re Tomaski’s post #3192, and subsequent discussions.
The points made are prefixed as ‘possible’, but subsequently argued as fact without supporting evidence.
Re MCAS design, from what has be been attributed to reliable description, the theory of MCAS is consistent with methods of enhancing stability shortfalls, e.g. Mach trim. However the design engineering implementation of MCAS, single system, etc, fell short of what was required or that which should have been detected - the debate goes on.
Re FAA weaknesses in oversight and certification process; most likely, but these deficiencies have been noted, investigated, and action is expected. They are central to the accidents, but apparently not unique - a continuing concern.
Re ‘glaring deficiencies’ in operator maintenance; the scant information relating to the accidents published so far indicates that maintenance activity could be judged as good as might be expected given the lack of published information about MCAS - or of its existence at all, at that time.
Re crew training relating to the accidents; no evidence provided at all. Pure supposition based on hindsight, reinforced by the ongoing debate as to how much credit should be allocated to crew intervention, alerting systems, procedures, and the apparent inability to manually move the trim from extreme positions.
These accidents should provide many lessons to be learnt; the first and very important is to beware hindsight bias.