The quote from Marc Moller seems counter to what I have seen as the prevailing thought regarding aviation accidents, which is: accidents are the result of a "chain" of failures; if any link in the chain does not occur the accident can be avoided. It is easy to say "software bug" or some single thing caused this failure, but there are many other factors that need to be considered: a/c certification requirements, training requirements (sim time, transitioning to new variants of an a/c), design philosophy for the Max, etc...
(Not an expert, but private pilot, have read many NTSB accident reports).