You're citing a very old thesis called 'Argentine exceptionalism' that was popularised in the 70s during the dictatorship years. It's been largely debunked today - The thesis did not consider wealth distribution or the wage worker status of the population. Argentina was one of the most unequal nations in the world, with 25% of GDP going to the top 1%. That's worse than the USA during the Great Depression. c. The convergence process of Argentina with Australia and Canada: 1875–2000, Isabel Sanz-Villarroya
You also linked a Wikipedia article, so I assume you accept it was a valid source.
You said the Great Depression hit Australia hard. The same article you linked says "Argentina was one of the most stable and conservative countries until the
Great Depression, after which it turned into one of the most unstable."
The same article notes that the decline began in the 1930s, not the 60s:
"Beginning in the 1930s, however, the Argentine economy deteriorated notably."
"However, the Depression permanently halted its economic expansion.
[51] Actually, much like other developing countries, the economy was already in a downturn beginning in 1927, a result of declining prices."
It also notes the differences in the economies; Argentina did not industrialise and much of its wealth was concentrated in the labour non-intensive livestock agriculture industry and so most workers didn't share in it:
"For all its success, by the 1920s Argentina was not an industrialized country by the standards of Britain, Germany or the United States.
[81] A major hindrance to full industrialisation was the lack of energy sources such as coal or
hydropower.
[81] Experiments with oil, discovered in 1907, had poor results.
[81] Yacimientos Petrolíferos Fiscales, the first state-owned oil company in Latin America,
[82] was founded in 1922 as a public company responsible for 51% of the oil production; the remaining 49% was in private hands.
[83]
Exports of frozen beef, especially to Great Britain, proved highly profitable after the invention of refrigerated ships in the 1870s.
[84] However Britain imposed new restrictions on meat imports in the late 1920s, which sharply reduced beef imports from Argentina. Ranchers responded by switching from pastoral to arable production, but there was lasting damage to the Argentine economy.
[85]"