While I do believe that one of the functions of a government is to encourage a diverse economy, I do not believe that it is the role of government to create it.

While I do believe that one of the functions of a government is to encourage a diverse economy, I do not believe that it is the role of government to create it. If there are people in (we'll use your example) Brisbane that are willing, able and capable to begin to build a tech industry, they should. After that has occurred, then the government is in a position to look at how it can best encourage continued growth. However, it may end up that Sydney is where Australia's tech industry takes root and grows through natural activity and movement instead of Brisbane. This is normal and it will happen. Not every city is 'world class' at everything, it's really not possible.