There is this widespread belief that scaling is based on subject difficulty and therefore you should get an "ATAR boost" in more difficult subjects to take advantage of the scaling. This is actually a myth.
The most obvious reason why it is a myth, is simply because it is not possible to measure "difficulty" objectively. The whole thing is driven by the student marks data and there is no pre-determination that one subject should scale more than another. It is the data that should tell us whether one subject scales better than another. In fact, the UAC calls this nuance out every year in their scaling reports lol. Unfortunately, so many people are making the correlation vs causation mistake. Maths Advanced scales better than Maths Standard NOT because it is harder, but because it has a stronger cohort on average (based on how they performed in their other subjects). This just happens to correlate with society accepting that Maths Advanced is a harder subject.
Hypothetically, if all the strongest students in the state did Maths Standard and all the weakest students in the state did Maths Advanced (i.e. we flip what happens in reality) then Maths Standard will actually have a higher scaled average than Maths Advanced, despite being the "easier" subject. This is why the academic says this is "how the system is supposed to work" (though I think that statement has been taken out of context in the article) because the data will tell us whether there are more stronger candidates doing Maths Standard vs Maths Advanced. The data seems to suggest that the gap between Maths Advanced and Maths Standard is not that wide, which is consistent with the observation that some of the more capable students have been choosing Maths Standard over Advanced.
On the broader issue of people doing Maths Advanced for tertiary study, people shouldn't rely on the scaling system to incentivise people to do Maths Advanced. It was never designed in that way. The scaling algorithm only figures out where the stronger versus weaker students in state are sitting (and unfortunately many of them seem to be doing Maths Standard). It really should be the universities and schools doing the incentivising. If schools/universities continue to incentivise capable students to do Maths Standard instead of Maths Advanced then we may actually get to the point where Maths Standard scales better than Maths Advanced… which then makes Maths Standard look very attractive to even more capable students and it's a downwards spiral from there.