Just to clarify, we'd be getting floods with or without dams. Some (not many) of the dams are there to reduce (but not completely stop) flooding affects. Wivenhoe (QLD)is a flood protection dam. Warragamba (NSW) is not, it's a water storage dam (with a side benefit of some flood reduction).

The flooding is just happening because of the wet (LA Nina) period we are having as you've suggested.

We can't insulate ourselves from flooding due to the dangerous rainfall events in the report (like PMP events). In the PMP event you mainly want the dam to safely pass the water and stay structurally sound. Dan failure is worse than any natural flood event.