Holden did poorly in the commercial vehicle market. Commodores back in the early 2000's were also very unreliable, which I have no doubt pushed people towards Toyota.
To say the Captiva alone killed Holden is stupid. Barina, Astra, Colorado were all seen as offering little value for money compared to a Camry, Hyundai or Hilux. Even the Ford Territory, which you hardly ever see on the road anymore, sold quite well.
Last, but not least, Toyota absolutely obliterated the 4WD market with its Land Cruiser.