I had decided to abstain from commenting on this subject further. Pretty much every reply I have received is a variation of ‘fake news’ or ‘racist cunt’.

Yeah, kneejerk reactions get tiring. I tend not to use reddit-like or twitter-like forums much because of how low-effort and unempathetic most posts are. 'Read the news title, get angry', might as well be the motto. I'm glad you appreciated it.

Affirmative action based on […] economic prosperity would help the most people in need and capture many more who would otherwise fall through the gaps.

This absolutely is and should be fought for, alongside other movements. The concentration of wealth at the top has just accelerated after the main COVID crisis. Our whole economic system funnels wealth to those with capital, and their influence on our political system and mass media is the root cause of most issues in our society. My caveat is that affirmative action re: economic prosperity won't solve this, the problem runs so deep that affirmative action will ultimately be inadequate, treating the symptoms rather than the cause. We need a systematic overhaul… far far far far easier said than done.

That said, economic equity doesn't cover everything, as many Indigenous people have other priorities that aren't strictly economic, a major one being land rights. A somewhat-known recent example of the issue is mining companies destroying sacred land or historical artifacts, another is traditional use of the land to live off of. I admittedly don't know enough about land right to explain in proper detail, but it's one of the main demands that protesters have demanded for decades and decades.

I would argue that abolishing slavery, universal suffrage, and anti-discrimination laws have done far more to solve systemic racism than racial affirmative action.

I agree, and I would say that this doesn't mean affirmative action isn't still important. To take a metaphor from the Civil Rights struggle, that anti-discrimination is taking the knife out, there is still a need to heal the wound before we can say things are fine. We've abolished the most blatant aggression like non-suffrage, but done very little to make amends on things like colonisation and centuries of repression and land possession.

Generations of loss and disadvantage evidently still exist, and will remain without positive interference. Disadvantage is cyclical, it doesn't heal by itself, poverty is an self-evident example of the cyclic nature of powerlessness. And to re-emphasise, this applies generally to disadvantage, not just disadvantage caused by colonisation or racial disadvantage.

As a side note, I'm not sure if it's even correct to frame this as about race, Indigenous classification just inherently matches up with race since the historical inhabitants of Australian land were all, to use a racial term, Black indigenous Australians, and we've historically just grouped them all together when it comes to the social concept of race because they're not White or Asian. The ill-advised and quite frankly worthless Voice proposal was about them being the native peoples, not about them being a certain race or having been racially discriminated.