The same reason underlying reason why the US has the largest gap. Austalia is not a threat to anyone, The US is a dominant power hence it is the candidate for any psyop attack.
Not just a size thing, it's also the cultural hegemony provided by things like Hollywood, big IT companies, explicit cultural exports, etc.
Australia is fundamentally in the US-led Anglosphere, and debates that originate in the US eventually flow to Canada, Australia, NZ, the UK, and to a lesser degree much of the US-aligned world (e.g. SK, Japan, Israel).
I think it makes a lot of sense for another superpower like China or Russia to "go to war" via social division rather than kinetic war. They couldn't succeed at a kinetic war, so the only alternative is to work to weaken or dismantle a country from within by sowing division amongst the population and manipulating the economy.
I don't think it is a theory. We have now decades of documented reports that Russia is targeting the USA sowing social discord. They don't care about any specific outlook, they will support both extreme right and extreme left as long as there is social conflict and polarization.
Kids should be learning about these things at school, they need to recognize attempts at polarizing, creating conflict, and make them perceive other members of their own society as enemies. Both young and older people are vulnerable as these "trolls" (which is not an appropriate name any longer btw) use some real social problems as a starting point and escalate them. And they're extremely successful in part because of social media apps algorithms that effectively act as amplifiers of extreme content.
Conspiracy theory? I was under the impression it's very well documented. Might not be everything, but you can see how a few million posts from troll farms/bots would sway the narrative to more extreme, and even the real people disagreeing might be doing so because they read a few too many of those posts.
