South Australia's energy grid is a very exceptional case, due to a very jarring transition to renewables. I would not expect the same level of returns in other areas.
The problems have been interconnects failing, poorly maintained transmission lines failing, the market operator placing restrictions on renewables which meant that renewables were not allowed to try to keep the lights on, and reliance of SA on electricity imported from unreliable interstate supply (aka coal thermal plants that break down or simply fail due to high ambient temperatures).
All of SA’s energy problems are due to poor regulation, poor market operation, poor maintenance, Federal interference, market gaming by fossil fuel operators, and unreliable coal plants.
There will be similar returns possible for other batteries in NSW (a net importer, thus highly vulnerable to gaming of the market) and QLD with a large installed base of unreliable coal which means increasing need for ancillary services.
Coal is not reliable to start with, and the plant currently in use is old and getting to the point of being no longer economically viable. NSW and QLD grids will need significant support services as they transition from unreliable coal to dependable (but intermittent) renewables.
While the transition to renewables has indeed been rapid and jarring, that's not what has caused problems.
More peaks doesn't mean worse all things considered, it isn't a critique, it's just saying that battery viability is highly contingent on local power mix.
https://www.aemo.com.au/-/media/Files/Electricity/NEM/Market...
Failure of a meshed power system cannot be attributed to the failure of any single sub-system. Rather it must be a combination of factors including those you just mentioned.
The dependence of the power system on renewables (specifically wind farms)contributed in two ways to the blackout:
1. The majority of wind turbines provide little or no system inertia. By displacing synchronous generation with wind generation, system inertia is reduced which results in greater ROCOF during an event where there is a change in active power demand/supply. In the SA blackout, fast ROCOF overwhelmed the system's last line of defence- under frequency load shedding.
2. Some wind turbines contained a fault ride-through setting which AEMO was apparently not aware of prior to the blackout. Specifically, the setting caused the turbines to disconnect after experiencing a sequence of voltage excursions within a set time period. The disconnection caused a loss of active power supply to the grid which contributed to the drop in frequency and eventual collapse.