The author of the article linked shows how if Hubei was locked down 1 day earlier, it might have reduced the cases by 20 000.
People saying this is "only" affecting 200 people in Australia are missing the point of the power of exponential growth. You shouldn't be counting from the front, as it were, but from the end. 1 week less, even 1 day less, of exponential growth will be unnoticeable in number of cases at the start of an epidemic, but can be huge by the end.
And we also have way more than 200 cases. Everywhere that has gotten to 200 cases, a week later has discovered they had many times this number. The article also shows how when they thought there were 444 cases in Wuhan, there were actually about 12 000. The number of official cases in Australia could be 10 or even 20 or 30 times lower than the actual number.
On top of all of this, we are getting coronavirus heading into our flu season, unlike the Northern Hemisphere countries. So if our medical system already struggles at peak flu season, adding coronavirus to the mix could be disastrous.
We absolutely have to take this seriously, right now, before it becomes unstoppable. Even a 0.5% death rate on top of our flu season would be bad, and that is an absolute best case scenario if we lock down our towns and cities right now (not on Monday, not just a suggestion, not just sporting events).
40% increase in cases overnight, if we keep that up we could get 1000 times as many infected in 3 weeks. If we have 2000 infected now, which is possible, that could be 2 million in just 3 weeks. If that happens, our medical system will absolutely be overwhelmed, and our elderly population will get close to the 7% that Italy has. And shortly after that we will enter flu season, but will have no medical spaces for people with the flu, which will make it one of the deadlier flu seasons.
We are talking about 150 000 + deaths in this country, most of us losing a loved one, if we don't start taking this seriously.
My prediction is in a week and a half we will get more serious, schools and public transport will close, and a week after that most shops. We won't have acted early enough to get the "good case" of "only" 0.5% deaths (and "only" tens of thousands of cases, so "only" a few hundred deaths, or a mild flu season, as people are saying). But that will hopefully stop catastrophic losses like I have suggested could happen.