Not sure of the exact formula that QF uses to decide if your resume is 'competitive' but its a case of the old airline recruiting standard...'age comensurate with experience'.
Qantas can't say this because Australia has age discrimination laws and if they did admit this they would be wide open for a breach of discrimination law. You may know a 23yo with 500hours who has got in but you wont find a 38yo with 500 hours with the same fortune.
For turbine dreamer and deckchair, i would say that at your age and with your experience your application would not quite fit the age v experience criteria, but don't stop trying, Qf have employed a 52yo direct entry SO, his experience was however substantial.
Hope that sheds some light.