(Update: Uh, there's something wrong in this post. A commenter points out that 3% of the votes will get you 3% of the seats, not a single seat like I say below. I don't think this changes much in the argument -- the math still works out to local seats being something like half as hard to scrounge up votes for, especially in by-elections. So while the math below is a bit off, I'm going to leave it as is.)
So, yeah. Apparently, the 3% threshold that Ontario's proposed system requires is too low, and it's going to create a forest of small parties, all of whom will collectively tear apart Ontario's politics. Because apparently massive political changes are made by parties with only one seat in Parliament.
Let's try some math, here.
In the 2003 Ontario general election, 4,497,244 people voted. For simplicity's sake let's say 4.5 million. 3% of 4.5 million is 135,000 votes. So in order for a party to get one list seat in the Legislature under MMP, they'd need to get 135,000 votes across the Province.
Meanwhile, in the actual 2003 election, we can see that actual ridings were won with vastly less voters. In London-Fanshawe, the Liberal candidate (Khalil Ramal) won with a total of 13,920 votes -- 0.31% of the vote, one-tenth as many votes required to win a hypothetical list seat. In the 2005 Scarborough-Rouge River by-election, Bas Balkissoon won his seat with 9,000 votes (0.2% of the 2003 provincial vote!) And remember, in the MMP system, the vast majority of ridings will still exist, only some of them will be larger. This will mean that slightly more voters will be needed to win a single riding, but not nearly enough to make up the difference between a riding and a list seat.
There's this idea out there that somehow, list seats will be "easier" to get. But elections are made by a party getting a bunch of people out to vote, and the fewer people you need to get voting for you, the easier it is to get a seat. Clearly, if you were a fringe party looking to spend some money to win a seat in the Legislature, grabbing a list seat would be the hardest possible way to do it. In terms of actual people voting, your money would be 15 times more effective in Scarborough-Rouge River (2005) and almost ten times more effective in London-Fanshawe (2003).
It's easy to underestimate how hard political campaigns actually are. They take a lot of money, and a lot of volunteers, and despite what Murray Campbell thinks, Youtube voters aren't particularly eager to throw their votes away. Indeed, those crazies he disparages are probably more engaged in the political process than most of his readers. Getting 3% of Ontarians to vote for you is really, really hard -- the Greens are the only "fringe" party that's come close, so far, and they only got 2.8% of the vote. The next runners-up, the Family Coalition Party, got 0.8% of the 2003 vote -- they'd have needed to quadruple their vote in order to get a single seat. (And once more, a single seat in Parliament and fifty cents will get you a phone call.)
For reference, here are the three party leaders, and the number of votes they got in their respective elections (Tory won a 2005 by-election):
Dalton McGuinty: 24,647 (0.55% of the 2003 Ontario vote.)
Howard Hampton: 15,666 (0.35% of the 2003 Ontario vote.)
John Tory: 15,633 (0.35% of the 2003 Ontario vote.)
Only one of the three party leaders who currently hold a seat at Queen's Park got even one-sixth as many votes as they'd need to win a list seat.