In 2005 if the single-electorate entitlement had not existed, United Future would have gained fewer seats and the Labour Government would have needed the support of both NZ First and the Green Party. NZ First's avowed refusal to work with the Greens could have denied Labour a third term.
In 2008 Act wouldn't have got four extra seats by winning Epsom, National would have got two fewer list seats and the Maori Party would have held the balance of power. That outcome would have been repeated at last year's election. By implication, National regards the Maori Party as a less reliable partner than Act or United Future.
MMP, as National reminds the commission, was designed to be a delicate balance between proportional representation and stable government. The party argues the balance is "fragile" and could easily be upset by the changes proposed. Parliament, it says, is already highly proportional with five or more parties usually represented and government stability has usually depended on a slim majority of one to three seats.
It's a fair point but a timid one. National seems not to want to disturb the status quo because it discounts its chances of finding stable coalition partners under the simplified system proposed. Yet lately, a new Conservative Party has gained ground in polls on the basis of its opposition to gay marriage. There's no reason to think the political right will not produce as many parties as the left.
National occupies the broad middle ground of the right, just as Labour does of the left, but it leaves room for more liberal and conservative parties on its side. Religious parties often find a niche in proportional politics and another might emerge in this country at any time. National is also leaving room for "blue-green" environmentalism, Act's libertarian instincts and NZ First's racial and economic protection.
Electoral rules that reward parties for winning a single seat have produced parties that depend too much on a single personality. If a single seat no longer carried a proportionate entitlement and they could aim at a lower national threshold, 4 per cent, they might become more soundly based, more durable and more capable of contributing to stable government. National should take that chance.