plenty of airlines do this .. one of the reasons being to cut costs by establishing a large local crew base at their foreign hubs .. e.g. NWA at Narita.
Qantas' Asian hub is in Singapore. Oz flights connect through SIN
to a myriad of destinations : kota kinabalu ( AO ) , bali ( AO ) , hkg ( used to on QF
77 per-sin-hkg ) , london , rome ( pulled ) , paris , and frankfurt. the number of qantas/ba/australian airlines planes in singapore gets really phenomenal during the evenings ... Singapore Changi Airport really has a very intimate orgy with up to 8-9 Kangaroos in the evening !
Emirates' Asian hub is also in Singapore, mainly connecting Europe/Middle Eastern passengers with SIN
-Oz flights. This is changing as Emirates is opting for non-stop services to Oz from their Dubai homebase.