Whatever political panic there was at the time, the battery didn't 'fix' the issue; repairing the poles and wires did most of that job.
As for SA 'reliance' on cables from the east.. yes, definitely! It's a 2-way street; they import and export (that's the point of the NEM though). A snapshot today shows they'd be exporting at the moment, for example:
https://www.sa.gov.au/topics/energy-and-environment/energy-supply/sas-electricity-supply-and-marketThey also had some crazy swing in wholesale costs over the last summer.. Prices were in the negative during many days, but there was a crazy spike in late December 21, for a couple of days.
Renewables remain peaky, there's no doubt there, but battery tech can level this out. Imagine having large scale VFRB's installed with 25+ year life and a much cheaper outlay than lithium?
Are SA 'there'? Not yet, but they are much further along the journey than AGL are.
(20min delay)