Boeing was caught flat-footed and underinvested in a new product in 2011.
So while Boeing management could have said "No" to their largest (?) customer, that would have been a hard decision to make. And probably would have led to the board chopping C* heads for breach of fiduciary duty.
The Airbus order backlog is almost a decade out as it is, so American just shoving it all into A320neos that would take longer to show up wouldn't exactly be realistic either.
Boeing should've just gone with a clean-sheet design.
Hindsight is 20/20. The CEO chose a risky payoff (Boeing remaining competitive with the Max) over certain loss (Boeing losing many contracts to competition).
If the CEO didn't expect jail time (which given our history of such incidents is unlikely), he chose rationally in his own self interest.
If you want a different outcome you need to disincentivize this kind of behavior. E.g. if CEOs "taking responsibility" (because that's usually the reasoning for their insane income) meant they get locked up in prison without parole for 20 years. Then rational actors may become more careful.
Of course every customer ever is always going to ask for products on a faster timeline at a cheaper price. That doesn't absolve the manufacturer of its responsibility to build a safe product.
And I'd be inclined to agree it's 100% manufacturer fault... except this was a pretty high pressure ask.
IMHO, for me, it crosses over the line into sharing some of the blame.
Yeah, because American doesn't deserve blame for this nearly to the extent that Boeing does.