I have a very different perspective on this. Australia has had more than just one Atlassian. They've also got Campaign Monitor, BigCommerce, Canva, Where 2 (became Google Maps), Envato. Australia is also growing Freelancer (I don't believe it was initially built here), and I'm sure many others.
Now, let's look at the comment regarding the newly announced innovation strategy does provide lots (probably too much) money to incubators, but so has every country. The incubator thing is just not successful outside a the few outliers YC, TechStars and maybe 1 or 2 others.
However, one of the large components of the plan is tax incentives to early stage investors. There are also bankruptcy law reform. There is also a new Entrepreneur Visa.
Now, Silicon Valley will almost always have an advantage to the history and network there. But that doesn't mean that Australia is "a crappy place" for tech business.
I find Australia a refreshing change from North America. There is a realistic view on revenue models, less money is 'wasted' on poorly thought out businesses. Australians are bright resourceful people.
I think this is a great place to be in tech. It punches above it's weight on the world stage.
If you look at regions with major technology successes, what do you end up with? A bunch in the US, a few in China, a few in India, a few in Canada, a few in Germany, a few in the UK. Where would Australia end up on a list of population vs. influence? I think pretty high.