Housing bubbles and social mercantilism

A two-part essay on the problems of social division and failures of urban planning and management using Sydney and Melbourne as "compare and contrast" examples is here:

Since 1990, owner-occupied and investment property credit has expanded its share of total credit from 23 per cent to 58 per cent. (Business credit has dropped from 63 to 34 per cent.) Australians have been taking on large amounts of debt to invest in houses whose prices are largely a product of quantity controls: Australia has become a country highly leveraged on regulatory approval

and here:

Sydney’s land policy in particular is based on the social mercantilist model—with the inequality, conflict, inequity and corruption that model is inherently prone to. Melbourne can be thankful that its better social dynamics have ameliorated the ill-effects of the same disastrous ideas.

The author should have made it a bit clearer that you can have housing bubbles without quantity controls, they just make them more likely (and possibly more severe).