recently installed in South Australia can supply enought energy to run South Australia for less than 2 minutes,

And just how long does it take to fire up a (eg) jet engine? The battery is there to cover the sudden dips that could cause a catastrophic run-away disconnect that plunges a whole area into power-outage. It is so easy to rubbish something, so much harder to think. And doesn't it have super capacitors that would supply power for a second or so? To save battery life from the most severe charge/discharge cycle.
In these days of internet dependent industry (& government) - security of power is critical - India does it piecemeal with heavily polluting diesel generators on every corner.

45 years ago the UK built a big battery that could power Manchester for 30 minutes. They called it Dinorwic**. And I bet in those days they could fire up slower in-fill capacity in that time.

**think pumped storage - hydro.