The QF flight timings are not ideal for Singapore-based pax. Eg SIN-PER arrives close to midnight. PER-SIN leaves at 0800 from Northern Summer.
This means a Singaporean family of 4 going to PER would need to spend 2 extra nights of accomodation on a holiday. And if you've young kids you won't want to check into your hotel at 1am and then check out at 5am to get to the airport for the 8am flight.