Earlier quoted context omitted.
True, but as integrator, Boeing is still responsible for ensuring the quality of the final product.
You can also argue that the airline is responsible for operating only quality products
- It's the assembler's responsibility to make sure the exit door bolts are properly tightened, and
- It's the manufacturer's responsibility to find assemblers that correctly tighten door bolts, and the manufacturer's responsibility to design doors that don't explode, and
- It's the airline's responsibility to find manufacturers that design planes with not exploding doors, which are assembled by assemblers that correctly tighten door bolts, and checked by the airline's own maintenance teams during regular servicing of the planes.
Everyone should be looking over and double-checking everyone else's work. But that's not how the 737 MAX was designed or built.