I am just going to say, be very careful what you are campaigning for. At the moment, yes there is a "cap" but Oz is still one of the easier countries (by a fair way) of bringing a spouse in and then having full PR. If the government felt it wasn't able to control in some way, it may well look at models used in other countries.
For example, in the UK the requirements are far harder. The sponsor has to prove one of two routes. That they have been earning a certain amount and have a permanent job offer earning over a specific amount. Or, they have £62500 in savings, held in cash for the last six months. And at the end of all that, the partner doesn't have anything like the rights of Oz PR. Oh, and they have restricted rights to many state elements. And it takes about the same time as Oz PR.