Basings/ Job-share / part time , whatever you want to call it, was being discussed in EK as far back as 1998 to my knowledge. Some of the Oz boys put a lot of effort into making a strong case financially and logistically but it was knocked back then at a higher level than DSVP (GJ and subsequently TCK), so the opposition predates - and probably comes from higher levels than, I suspect - TCAS by some considerable time.
That's not to say that current circumstances would not justify it, and I know some major EU carriers enable the boys and girls approaching retirement to go on 50 per cent hours as a gentle intro to life in the rocking chair!
7B