In order to match Quebec's 21 Liberal Seats, you need to add up the next three provinces. BC, NS, and NB.
Let's go back four years to 2000.
Ontario 100 Liberal Seats. Quebec 36 Liberal Seats. Cumatively enough to form a minority goverment. The rest of the country together only elected 36 Liberal Seats.
Let's go back to the elections of 1997
Ontario 101 Liberal Seats. Querbec 26 seats. The rest of Canada 37 Liberal seats.
Notice a pattern? Ontario the largest supporter, followed by Quebec. Still think Quebec has nothing to do with it?