A likely reason - The only people that would work for Cathay and Dragonair are either cadets, or the incredibly inexperienced. A Cat D simulator removes any requirement for Base training for suitably qualified pilots.
JP JP,
Its an ‘across the board’ requirement, regardless of prior experience. I’m also told it’s an Airbus requirement on initial conversion to wide body with no prior narrow body jet time.
QF did away with it on the 767 from around 2006 on - unsure what current requirement would be for FO upgrade onto the Boeing widebodies there.