Reference who does what...
I recall many years ago when I was in training on the L1011 that the company had the Captain doing all the vital (and some not so vital) actions, whereas the First Officer was ah....not doing much, except to call for the fire services in the case of a fire on ground.
When I asked the fleet manager why, his reply was...'we know the limitations of our more junior crew members so we hire experienced Captains who know the score.'
Could it be that Boeing has left the decision of who does what to the individual airline, considering that they might recognise that one size does not necessarily fit all...IE: skills levels differ depending on operating experience?