Flex lines were introduced as a way to assist with 'reduced flying hours'.
If you hire pilots to fly aircraft and then decide to park them BY THE DOZEN around the world either to look pretty on tarmacs (the new ones) or cut them up (at VCV) then you are going to have too many pilots.
'Flex Lines' were the first step on the ladder to VR and (I have no doubt) CR.
Look at it another way.
If Qantas was expanding (i.e. being run properly) the way EK, ANZ, CK etc etc are and announcing near record profits with pilots and airframes flying flat out (as they mostly have been since, gee when was it? - Thats right, when Dixon arrived!) what do you think the response might be if Pilots requested to only fly one trip a month? I don't think I would be going all that far out on a limb in saying the response would be along the lines of 'Get Stuffed! Oh, and BTW, you are leaving on a BKK-LHR at 1400 this afternoon!'