Talk of a $5M Cap on Superannuation Balances., page-151

The tax savings were what was used to sell it to the government. There is another purpose for it to come about.

Liability. The amount of multi million $ accounts is growing. The Superannuation Body and some funds themselves are pushing for this.

Think along the same lines as the banks. Banks don't want the liability of large balances, it's why only $250k is guaranteed.