I certainly agree that some of the stories from CX and others seem strange. The fact is that there has always been a difference in upgrade failure rates between long haul and short haul pilots. The BEA/BOAC contrast way back when was stark and explained in part by the additional handling experience on short sectors.
Emirates has tried to avoid this by insisting on a certain level of experience for new FOs. Another factor is that in a smallish airline everyone knows everyone else. With thousands of pilots, management may well only have heard of someone for the wrong reasons.
These things also tend to become self perpetuating. If you go through such a system when you get into a situation of power you expect others to do what you did. At the end of the day CX obviously feel they can still afford a system which is inherently wasteful in this way.