Originally Posted by
ST Dog
Because buyers don't want to retrain pilots.
If the OE wants to sell aircraft they have to build what the customers want. If that means maintaining the type cert, that's what they will do.
If the buyer buys a competitors aircraft after using 737 NGs it is going to have to retrain its crews too.
A difference course from NG to Max including MCAS normal and failure modes is a lot less training than a complete ab initio on the A320, so they save on training anyway.
Boeing made a mistake when giving the no-training guarantee - and that led to the stressful situation they are now in.