No it's not rubbish...and it has everything to do with Australia. It's a middle east thing if Hong Kong and Bangkok are in the middle east too then. If it's not an Australian regulation then explain to me why when boarding a flight to Australia in Hong Kong, after having your boarding pass scanned you then have your carry on bags rummaged through by security personnel and there are bins full of bottles of water, whereas boarding a flight to London, also from HKG, this does not happen.
Anyway, you can read about Australia's inbound security requirements here:
Restrictions for inbound flights to Australia
The only method by which liquids (>100ml) can be taken onboard is when the shop delivers them to the gate for you...this happens in Singapore for example bacuase security screening has always been at the gate lounges in SIN, therefore they would have no duty free industry left otherwise!
Just to be clear that the Australian regulations forbid you to take your own, purchased after security, liquids onboard the aircraft it goes on to say: