There's more to it, like migration of between 100k and 300k a year, to flatten the curve on the retirement wave and ratio of workers to non-workers, but also to keep the housing construction market going.
In Perth, when the government grants were being handed out, at some stage there was hardly a single property less than 400k, now in some of the less desireable areas you can get detatched houses down to as low as 200k.
Just this week, the bank stress test on mortgage lending increases from 2.5% to 3% tolerance to rate increase, lessening the amount that can be borrowed.
It's all over the place, but as y say the tax system has created the concept where a dwelling is an investment and it skews the whole market.
Renting looks pretty attractive at times, but the nature of tenancy agreements in Australia is 6 to 12 months terms with invasive property inspections on a regular basis, nothing like the european model with 10 year terms and decorate at will.
This also drives a desire for home ownership for families as if they don't want to pay for private schools then there is competition to get into suburbs with the better government schools, and even without this they want sme long term certainty such that if they move suburbs they won't have to change childrens schools.