I was told long ago that the water was needed to support the stalks (over the last 20K or so years humans have engineered edible grasses to have absurdly large seeds).
But I guess that isn't the case.
But I guess that isn't the case.
Bali has reliably warmer weather than the Riverina in the winter months, so at a guess insulation would be less relevant for Balinese farmers.
[0] Australian rice growing is good for comparison because it necessarily has to be more water efficient and is more heavily industrialised than Indonesia