Was the 1989 Sydney Morning Herald wrong?

Yesterday I read a special Sydney Morning Herald article from the end of August 1989 to commemorate fifty years sicne the outbreak of World War II.

Such a finding is of itself nothing to seriously note, except that I found a very interesting article about how, contrary to what was believed at the time, Japan's imperial government had never planned an actual invasion of Australia, as apparently some 1980s historians thought. It said that Japan would have required a full twelve divisions for an invasion of Australia, and that doing so would have necessitated a diversion of huge numbers of troops away from the war being fought with China over Manchuria. The article also said that the Japanese would have, despite the absence of opposition to invasion in the north of Australia, had a great deal of trouble with an invasion of Australia because of the extremely harsh environment in the north and centre of the continent, to which their troops would have been completely unsuited. The Sydney Morning Herald said that Australia's military would have had a major advantage had their been a war on our soil, which even with the climatic differences compared to Australia's milder southern regions,

What I cannot agree with is the idea that there would have been no point for Japan to try to invade Australia, for reasons relating to Australia's vast and still not-fully-explored mineral resources. However, in the years of the Great Depression, the proportion of Australia's economy contributed by mining reached its lowest level on record, and it has risen since.

Because of this fact, the Imperial Japanese would naturally have failed to realise how much benefit they could have gained from invading Australia. If the Japanese had succeeded in gaining control of Australia's metal ores, there would have been a chance to monopolise valuable industrial resources that would have been as valuable in peacetime as in war, which would have given them an economic power far greater than they gained from the postwar "economic miracle". The history of Europe and East Asia after the war shows how a boom in a resource-free nation cannot be sustained because of the cultural changes no industrialising nation except those with abundant flat land has ever escaped. (In this context, it is interesting to see what effect Federation in 1901 had on Britain's twentieth-century history by removing Australia's enormous undiscovered resources?)